M. Duffy

6th Year Physics: Mechanics Theory

2013 OL Q5(a)

(a) Give an example of (i) a vector quantity, (ii) a scalar quantity. 7 or 4 correct examples of each 4 + 3 partial answer e.g. examples in reverse order, definitions given (4)

2013 OL Q6

Define (a) momentum, (b) force 2(6 or 3) (a) mass (multiplied by) velocity // mv 6 partial answer e.g. m, v (3) (b) mass (multiplied by) acceleration // ma // causes acceleration 6 partial answer e.g. m, a (3) State the principle of conservation of momentum 2×3 (total) momentum before (interaction) // m1u1 + m2u2 3 equal to (total) momentum after (interaction) // = m1v1 + m2v2 3 partial answer e.g. incomplete equation (3) Explain how the principle of conservation of momentum applies in the case of a jet engine moving an aircraft. 2×3 (backward) momentum of air equal to 3 (forward) momentum of aircraft 3 marks may be obtained from a diagram partial answer e.g. incomplete answer (3)

A truck of mass 5000 kg is moving with a velocity 10 m s−1 when it collides with a stationary car with a mass of 1000 kg. The truck and the car then move off together.

(vi) When the truck hits the back of the car the driver’s airbag inflates. The airbag deflates when it is hit by the driver’s head. Explain why the airbag reduces the risk of injury to the driver.? 6 or 3 any relevant answer e.g. longer time reduced force on driver’s head 6 partial answer e. g. refers to force, (3)

2013 OL Q12(a)

Part (a) Define pressure. 6 or 3

pressure is the force per unit area //P= FA 6

partial answer e.g. incomplete equation, refers to force, etc. (3) Describe an experiment to show that the atmosphere exerts pressure. (3×3) apparatus: can (containing water) // can (of air) // glass of water 3 procedure: boil water in can // pump // cardboard / lid seal / invert in cold water // air out // invert 3 observation/conclusion: can crushes / collapses // lid supported 3 labelled diagram may merit marks accept valid alternatives partial answer (3)

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2013 HL Q5(b)

(b) State the law of conservation of momentum. momentum before = momentum after 4 in a closed system / provided no external forces act 3

2013 HL Q6

(i) State Newton’s law of universal gravitation.

force proportional to product of masses // F∝Gm1 m2

d2 / F=Gm1 m2

d2 3

inversely proportional to square of distance // correct notation given 3 (ii) Explain what is meant by angular velocity. Derive an equation for the angular velocity of an object in terms of its linear velocity when the object moves in a circle.

rate of change of angle // θt and correct notation given 3

ω=θt (stated or implied) 3

ω= vtrt /

vr 3

(iv) Name the type of acceleration that the ISS experiences as it travels in a circular orbit around the earth. centripetal / gravitational 3 What force provides this acceleration? gravitational (do not accept “gravity”) 3 (vi) If the value of the acceleration due to gravity on the ISS is 8.63 m s−2, why do occupants of the ISS experience apparent weightlessness? they are in freefall // ISS accelerating at the same rate as occupants 3

2013 HL Q11

(c) Draw a diagram to show the forces acting on the suspended mass when the seismometer is at rest. weight acting downwards tension acting upwards 4 + 3 (–1 if vectors unequal; –3 for incorrect additional forces) (e) What type of motion does the frame have when it moves relative to the mass? simple harmonic motion 7 (award 4 marks for “wave motion” or “periodic motion” or “up-down motion”)

2013 HL Q12(a)

(a) State the law of conservation of energy. energy is neither created nor destroyed 4

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2012 OL Q5(b) (c)

(b) Give one factor on which the potential energy of a body depends, 7 or 4 m/g /h , etc. one correct 7 partial answer (4)

(c) Which of the following instruments can be used to measure atmospheric pressure? 7 barometer 7

2012 OL Q6

What is meant by the term ‘acceleration due to gravity’? 6 or 3 (acceleration) caused by the (gravitational pull of the) earth /moon /planet

6 partial answer e.g. refers to earth / refers to falling / 9.8

(3)

(v) Would the engine of the module be able to lift it off the earth’s surface? Justify your answer in terms of the forces acting on the module. 3 + 6 no 3Force required to overcome the earth’s gravity (5880 N) is greater than the upward force (2000) // 5880 > 2000 6 partial answer (3)

(vi) Why is the acceleration due to gravity on the moon less than the acceleration due to gravity on the earth? 5 or 3 because the mass of the moon is less than the mass of the earth

5 partial answer e. g. refers to mass / distance (3)

(vii) Suggest a reason why the module of the spacecraft when launched from the moon does not need a streamlined shape like those that are launched from earth. 3 no atmosphere // no drag // no friction 3

2012 OL Q12(a)

Part (a) State the principle of conservation of momentum. 6 or 3 momentum before = momentum after // m1 u1 + m2 u2 = m1 v1 + m2 v2

6partial answer e.g. incomplete equation // in a closed system

(3)

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A cannon of mass 1500 kg containing a cannonball of mass 80 kg was at rest on a horizontal surface as shown. The cannonball was fired from the cannon with an initial horizontal velocity of 60 m s–1 and the cannon recoiled.

Why did the cannon recoil? 4 to conserve momentum / to balance the cannon ball going forward

4

Why will the cannon come to a stop in a shorter distance that the cannonball? 6 or 3 bigger mass / resistance of ground bigger than that of air / small recoil velocity

6 partial answer (3)2012 HL Q5(b)

(b) A pendulum moves with simple harmonic motion. Give another example of a body that moves with SHM.any valid answer, e.g. a mass oscillating on a spring

7

2012 HL Q11

(b) Why is it not possible to extract all of the energy in the wind striking a wind turbine blade?

wind is slowed down 4rather than stopped 3

(h) Name one other renewable source of energy.

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any valid answer, e.g. geothermal, solar, etc. 7

2012 HL Q12(a)

(a) An Olympic hammer thrower swings a mass of 7.26 kg at the end of a light inextensible wire in a circular motion. In the final complete swing, the hammer moves at a constant speed and takes 0.8 s to complete a circle of radius 2.0 m.

(ii) Even though the hammer moves at a constant speed, it accelerates. Explain.

direction changes (continuously) 4

2011 OL Q5(a) What is friction? 7 or 4

force that resists motion // force between two bodies in contact // example 7

partial answer (4)

(b) What is the relationship between G, the gravitational constant and g, the acceleration due to gravity? 7 or 4

partial answer (4)

(c) A crowbar is an example of a lever; give another example of a lever. 7 or 4

any other lever e.g. door handle, scissors, wheelbarrow, tongs etc ,one correct 7

partial answer e.g. metre stick (4)

(j) Give a disadvantage of a named renewable source of energy? 7 or 4

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biomass/ tide /sun / wind is not always there 7valid alternativespartial answer e.g. named source (4)

2011 OL Q6

State Newton’s first law of motion. 6 or 3

A body will remain at rest or moving at a constant velocity unless acted onby an (external) force 6partial answer e.g. incomplete answer, Newton’s 2nd or 3rd law (3)

A car of mass 1400kg was travelling with a constant speed of 15 m s-1 when it struck a tree and came to a complete stop in 0.4s.

(v) What happened to the kinetic energy of the moving car? 3 x 3

converted to heatconverted to soundconverted to potential energyused to deform car / tree

two lines correct 3 x 3one line correct (2 x 3)partial answer (3)

(vi) A back seat passenger could injure other occupants during a collision.Explain, with reference to Newton’s laws of motion, how this could occur. How is this risk of injury minimised? 4 or 2 + 7

states or implies use of Newton’s law(s) in explanation 4

partial answer (2)by wearing a seat belt. 7

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2011 OL Q12(a)

(a) State Boyle’s law. 6 or 3

(for a fixed mass of gas kept at a constant temperature) the pressure isinversely proportional to the volume // PV = k (when T and m are fixed)

6partial answer e.g. incomplete statement

(3)

Describe an experiment to demonstrate that the atmosphere exerts pressure 4 x 3

apparatus: can (containing water) // can (of air) // glass of water 3

procedure: boil water in can // pump // cardboard / lid 3

seal / invert in cold water // air out // invert 3

observation/conclusion: can crushes / collapses // lid supported 3

marks may be obtained from a diagramvalid alternatives

2011 HL Q5(b)

(b) Why does the value of g, acceleration due to gravity, vary at different locations on the surface on the earth?locations are at different distances from the earth’s centre / earth is not perfectly spherical / etc. 7

2011 HL Q6(a) Define the moment of a force.(T = ) force × (perp) distance / F × d

6

When the toy is knocked over, it always returns to the upright position. Explain why this happens.(toy non-vertical) c.g. has a (turning) moment about fulcrum / point of support/contact /(c.g. has) zero turning moment when toy is in vertical position

6

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(any valid reference, e.g. ‘low c.g.’, ‘equilibrium’, ‘turning moment’, … 3 marks)

(b) State the conditions necessary for the equilibrium of a body under a set of co-planar forces.(vector/algebraic) sum of the forces = zero // forces up = forces down // ΣF = 0sum of the (turning) moments (about any point) = zero // CTM = ACTM // ΣT = 0

6+3

(c) A simple merry-go-round consists of a flat disc that is rotated horizontally. A child of mass 32 kg stands at the edge of the merry-go-round, 2.2 metres from its centre. The force of friction acting on the child is 50 N.

If there was no force of friction between the child and the merry-go-round,in what direction would the child move as the merry-go-round starts to rotate?child remains stationary / any appropriate answer, e.g. ‘it depends on the frame of reference’ 5

2011 HL Q12(a)(a) State Hooke’s law.(restoring) force proportional // F ∝ –s / F = – k s

3displacement / distance // correct notation for F and s

3

A body of mass 250 g vibrates on a horizontal surface and its motion isdescribed by the equation a = – 16 s, where s is the displacement of the bodyfrom its equilibrium position. The amplitude of each vibration is 5 cm.

Why does the body vibrate with simple harmonic motion? (6)

acceleration proportional to displacement / a ∝ (-) s 6

2010 OL Q5

(a) State Boyle’s law 7 or 4(for a fixed mass of gas kept at a constant temperature) the pressure is inversely

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proportional to the volume // PV = k (when T and m are fixed) 7partial answer e.g. incomplete statement (4)

(c) State Archimedes’ Principle 7 or 4(when a body is immersed in a fluid/liquid it experiences an) upthrust equal(in size) to the weight of the fluid displaced 7partial answer e.g. incomplete statement / mention of upthrust (4)

2010 OL Q6

Define (a) momentum (b) kinetic energy 2(6 or 3)momentum = (mass)(velocity) // p = mv 6partial answer (3)kinetic energy: energy due to motion // 6partial answer (3)

State the principle of conservation of momentum. Explain how this principleapplies in launching a spacecraft. 3 3+ 3momentum before = momentum after // m1 u1 + m2 u2 = m1 v1 + m2 v2 3 3deduct 3 marks for each errorpartial answer e.g. incomplete equation // in a closed system (3)momentum of rocket equal but opposite to rocket exhaust 3

2010 HL Q5 (a)

(a) What are the two conditions for the equilibrium of a set of co-planar forces?forces up = forces down // (algebraic) sum of forces acting is zero 4(algebraic) sum of the moments (of the forces about any point) is zero 3

2010 HL 6

State Newton’s law of universal gravitation.

force proportional to product of masses

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(F) inversely/indirectly proportional to square of the distance // correct notation 3

A spacecraft carrying astronauts is on a straight line flight from the earth to the moon and after awhile its engines are turned off.

(i) Explain why the spacecraft continues on its journey to the moon, even though theengines are turned off.reference to Newton’s 1st law of motion / ‘because of its momentum/inertia’ 6(ii) Describe the variation in the weight of the astronauts as they travel to the moon.weight decreases (to zero) as the astronaut moves away from the earth 3gains (a lesser than normal) weight as she/he approaches the moon 3(v) Why is there no atmosphere on the moon?gravitational force too weak (to sustain atmosphere) 5

2010 HL Q12(a)(a)(i) A student holds a motion sensor attached to a data-logger and its calculator. List the instructionsyou should give the student so that the calculator will display the graph shown in Figure 1.stand 1 m from wall (and select START) 3stationary for 5 s 3move back to 3 m (from wall) in 6 s / accept specific velocity and time/distance 3stationary for 7 s 3approach to 1 m in 4 s 2

2009 OL Q5

(a) State the principle of conservation of momentum 7 or 4momentum before = momentum after // m1 u1 + m2 u2 = m1 v1 + m2 v2 7partial answer; e.g. incomplete equation // in a closed system (4)

(c) Which of the following is the unit of energy? 7kilogram watt joule amperejoule 7

2009 OL Q6

Define (i) velocity, (ii) friction 2 x 3velocity: rate of change of displacement // distance÷ time in given direction 3friction: force which resists (relative) motion (between surfaces in contact ) 3(vi) What happened to the kinetic energy lost by the train? 6 or 3converted to other forms of energy / heat / sound / sparks 6partial answer; e.g. converted (3)(vii) Name the forces A and B acting on the train shown in the diagram 2 x 2A = friction/retardation / resistance to motion 2

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B = weight / force of gravity 2(viii) What would happen to the train when the force A is equal to force T? 4 or 2train will move at constant speed / no acceleration / will not speed up 4partial answer (2)

2009 OL Q12(a)Part (a)Define pressure 2 × 3force 3per unit area 3

or (2×3)partial answer; e.g. area (3)Describe an experiment to show that the pressure in a liquid increases with depth 4 × 3apparatus: (tall) container, liquid, tubing and funnel // (tall) container, liquid 3detector e.g. pressure sensor, manometer // holes at different levels 3procedure: connect the tubing to the funnel and the detector. Insert the funnel intothe liquid and note the pressure. Repeat for different depths and notepressure at each depth // fill container above the holes 3observation/conclusion: note the pressure increases as the depth increases 3marks may be obtained from a diagrampartial answer (3)

2009 HL Q5(a) State Boyle’s law.pressure is inversely proportional to volume // P α

1V // P V = constant (= k) 4

fixed mass of gas at constant temperature 3(b) The moon orbits the earth. What is the relationship between the period of the moon and theradius of its orbit?T ∝ // T 2 ∝ // period squared is proportional to // 4√R3 // R3 // radius cubed 3

2009 HL Q6

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2009 Q12(a)State Hooke’s law.(restoring) force proportional to // F = -kx 3extension / displacement // correct notation 3

The sphere is then pulled down until the spring’s length has increased to 350 mm and isthen released.Describe the motion of the sphere when it is released.acceleration proportional to 2displacement 2(‘It executes/performs simple harmonic motion / S.H.M.’ ... 4 marks)

2008 OL Q5(a) State the principle of conservation of momentum 7 or 4 momentum

before = momentum after // m1 u1 + m2 u2 = m1 v1 + m2 v2

7 partial answer e.g. incomplete equation // in a closed system

(4) (c) Which of the following is the unit of energy? 7

Kelvin Watt newton joule Joule 7

2008 OL Q6The weight of an object is due to the gravitational force acting on it. Newton investigated the factors which affect this force.

Define force and give the unit of force 2(3 × 3)

(force) causes / changes // (rate of ) change of 3 acceleration // momentum 3

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partial answer e.g. change shape (3) Unit: newton / N 3

State Newton’s law of universal gravitation. force proportional / F∝ 3 product of masses / m1m2 3

inversely proportional to the square of the distance between them / 3

partial answer e.g. reference to G (3)

A powerful rocket is required to leave the surface of the earth. A less powerful rocket is required to leave the surface of the moon. Explain why 6 or 3

any reference to gravity less on moon // less force needed (to escape) // rocket does not need as high a velocity (to escape moon as its gravity is less) 6

partial answer e.g. moon is smaller (3)

2008 OL Q12Part (a) Define (i) velocity, (ii) acceleration. 6 + 3 (i) change in displacement with respect to time

(ii) change in velocity with respect to time

two lines correct 6 + 3 one line correct (6) partial e.g. change in velocity (3)

2008 HL Q5(a) State the law of flotation.

(when a body floats,) its weight equals 4

the weight of fluid/liquid/water displaced (–1 if ‘weight’ term not used) 3

2008 HL Q6

State Newton’s law of universal gravitation. force proportional to product of masses // correct relationship for F, masses and d 3 inversely proportional to square of distance // correct notation (-1 for each one omitted) 3 The international space station (ISS) moves in a circular orbit around the equator at a height of 400 km. What type of force is required to keep the ISS in orbit?

centripetal (force) / gravitational (force) 3 What is the direction of this force?

towards the centre (of the orbit) / inwards / towards the earth 3 An astronaut in the ISS appears weightless. Explain why. any correct relevant answer, e.g. he/she is in a state of free-fall; there is no contact force; force of gravity is the only force acting; force of gravity cannot be felt; etc. 3

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After an orbit, the ISS will be above a different point on the earth’s surface. Explain why. ISS has a different period to that of the earth’s rotation / not in geostationary orbit /etc. any one 6

2008 HL Q11(b) Define the newton, the unit of force.

(the force that) gives a mass of 1 kg // F = m a 4

an acceleration of 1 m s–2 // F = 1 N when m = 1 kg and a = 1 m s–2 3

2008 HL Q12(a) State the principle of conservation of energy. energy cannot be created // total energy of an isolated system / sum of K.E + P.E 2 nor destroyed // remains constant 2

2007 OL Q5(a) State Newton’s second law of motion 7 or 4rate of change of momentum is directly proportional to the applied force // F = ma 7partial answer (4)

(b) Which of the following is not a renewable source of energy?wind nuclear solar hydroelectric 7nuclear 7

2007 OL Q6Define (i) work, (ii) power, and give the unit of measurement for each one 2(3 × 3)(i) work 3 × 3( work is done when a ) force // formula 3moves (an object / its point of application) // notation 3partial answer e.g. energy (3)Units: joule / N m 3(ii) power 3 × 3work /energy // formula 3rate of / per second // notation 3partial answer (3)Units: watt / J s-1 3

What is the difference between potential energy and kinetic energy? 2 × 3

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potential energy is (energy a body has) due to its position/condition/state / mgh /example 3kinetic energy is (energy a body has) due to its motion / ½ mv 2 / example 3partial answer (3)Give two disadvantages of using a lift. 5 or 3needs more energy / uses energy / no exercise so not good for health /cost involved / can be dangerous, etc. any two 5any one (3)

2007 OL Q12Part (a)State the principle of conservation of momentum 7 or 4momentum before = momentum after // m1 u1 + m2 u2 = m1 v1 + m2 v2 7partial e.g. incomplete equation // in a closed system // law of conservation of energy (4)A rocket is launched by expelling gas from its engines. Use the principle ofconservation of momentum to explain why a rocket rises 6 + 3gas moves down (with a momentum)causing the rocket to move up (in the opposite direction with an equal momentum)two lines correct 6 + 3one line correct (6)partial e.g. same momentum / opposite direction (3)

Part (b)(i) Define pressure 2 × 3Force / F (over) 3divided by area / A 3partial answer e.g. Pa (3)Describe an experiment to demonstrate that the atmosphere exerts pressure 2 × 3 + 2apparatus: glass of water and cardboard // can of water and heat source 3procedure: place cardboard over glass and invert // boil water and put on lid 3observation/conclusion: water remains in glass // can collapses 2accept valid alternatives e.g. sucking out air methodslabelled diagrams may merit full marks(ii) State Boyle’s law 2 × 3pressure // PV 3inversely proportional to volume // = constant 3partial answer e.g. for fixed mass of gas // if temperature remains same (3)What will happen to the balloon as it continues to rise? 2(it will continue to) expand // burst // cool 2

2007 HL Q5(a) State Archimedes’ principle.upthrust / buoyancy / (apparent) loss in weight (in fluid) equals 4weight of fluid/ liquid/water displaced 3

2007 HL Q6State Hooke’s law.

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restoring force proportional to // F = ( -) ks 3extension/displacement // correct notation 3Derive the relationship between the acceleration of the sphere and its displacement from the fixed point.F = m a 3ma = - ks 2 x 3

⇒ a = - (k/m)s or a α -s or a = -(constant)s ( penalty of -1 if negative sign omitted) 3Why does the sphere oscillate with simple harmonic motion?its acceleration is proportional to // a = -ω2s or a α –s ( penalty of -1 , once only, if negative sign omitted) 3its displacement (from a fixed point and always directed towards that point) // correct notation 3( 2 x 3 for conventional definition of S.H.M)

2007 Q12(a)(a) What is friction?a force 3that opposes motion / tries to prevent one surface sliding over another 3

2006 OL Q5(b) Which one of the following instruments can be used to measure the density of a liquid? barometer hydrometer thermometer 7 hydrometer 7

(c) What is friction? 7 or 4 force (which) opposes motion 7 partial answer e.g. force / opposes / incomplete answer / example (4)

2006 OL Q6Define the term force and give the unit in which force is measured. 3 × 3 causes / changes // changes 3 acceleration // velocity / momentum 3 F = ma (2×3) partial answer e.g. example (3) N/ newton 3

Force is a vector quantity. Explain what this means. 6 or 3 (quantity with magnitude and) direction 6 partial answer e.g. magnitude (3) Give two factors which affect the size of the gravitation force between two bodies. 6 + 3 mass distance two correct 6+3 one correct (6) partial answer e.g. gravitational constant / G / weight (3)

Explain the term acceleration due to gravity, g. 6 + 3 object in free fall / due to the pull/weight of the earth 6

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increase in velocity per second / change in velocity per second 3 partial answer e.g. speeding up / weight / 9.8 (3) Why is the astronaut’s weight greater on earth than on the moon? 5 or 3 acceleration due to gravity is greater on the earth // mass of the earth is greater than the mass of the moon 5 partial answer e.g. reference to (acceleration due to) gravity // different masses of earth and moon (3) The earth is surrounded by a layer of air, called its atmosphere. Explain why the moon does not have an atmosphere. 3 (acceleration due to) gravity is less / mass (of the moon) is less 3

2006 HL Q12(a)Part (a) Define the moment of a force. 6 or 3 force (multiplied) by distance 6 partial answer e.g. force (multiplied) by / distance (3) Give one condition that is necessary for the crane to be in equilibrium. 2 × 3 clockwise moments 3 equal anticlockwise moments 3 partial answer e.g. it is balanced (3) A crane is an example of a lever. Give another example of a lever. 4 crowbar / nailbar / nutcracker / wheelbarrow / tongs / door handle / weighing scales / tools, etc. 4

2006 HL Q5(a) State Newton’s third law of motion. (7) action and reaction are equal // when body A exerts a force on body B, B exerts 4 a force equal in magnitude (and) opposite // (but) opposite in direction (on A) 3

(b) Why is it easier to turn a nut using a longer spanner than a shorter one? (7) greater torque / (turning) moment /turning effect

7 ‘distance from effort to fulcrum is greater’ (4)

2006HL Q6Define (i) velocity, (ii) angular velocity. (12)

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Draw a diagram to show the forces acting on the ball when it is at position A. (6) weight (W)downwards; force( F ) /reaction (R) upwards (-1 if either force omitted) 3 centripetal force to left (due to friction or curled fingers) 3 (description without diagram … -1)

2006 HL Q12(a)(a) Define pressure. (6) force // F /A 3 per unit area // explain notation 3 Is pressure a vector quantity or a scalar quantity? Justify your answer. (6) scalar 3 it acts in all directions / it has no direction 3 State Boyle’s law. (6) P α 1/V // PV = constant 3 for a fixed mass of gas at constant temperature 3

2005 OL Q5(a) State the principle of conservation of momentum 7 or 4 momentum before = momentum after // m1 u1 + m2u2 = m1 v1 + m2v2 7 (total) momentum is conserved (7) partial answer e.g. incomplete equation, in a closed system (4)

(c) Which of the following is the unit of power? 7 or 4 watt 7 joule (4)

2005 OL Q6Define pressure and give the unit of pressure 3 × 3 + 3 force / F 3 per / divided by 3 unit area / A 3 N m-2 / Pascal / Pa, bar, etc. 3 Name an instrument used to measure pressure 5 or 3 (pressure) gauge, (bourdon) gauge, manometer, pressure sensor, barometer any one 5 partial answer (3)

What holds this layer of air close to the Earth? 6 or 3

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gravity / gravitational force / weight 6 partial answer e.g. mass (3) Describe an experiment to show that the atmosphere exerts pressure 4 × 3 apparatus: can (containing water) // can (of air) // glass of water 3 procedure: boil water in can // pump // cardboard / lid 3

seal / invert in cold water // air out // invert 3 observation/conclusion: can crushes / collapses // lid supported 3 labelled diagram may merit marks accept valid alternatives Describe the kind of weather we get when the atmospheric pressure is high 6 or 3 dry, good, clear skies, little wind, settled / calm, etc. any one 6 partial answer (3) Why would the pressure on the ground be greater if the elephant stood up on just two feet? 2 × 3 area / A 3 less / smaller 3 partial answer (3)

2005 OL Q11(a) Define energy 7 or 4

ability to do work two lines 7 one line (4) partial answer e.g. valid energy equation, states the law of conservation of energy (4)

(b) What energy conversion takes place when a fuel is burnt? 7 or 4 chemical to heat / light two lines 7 one line (4)

(c) Name one method of producing electricity 7 or 4 solar, wind, wave, tidal, biomass, coal, oil, gas, hydroelectricity, geothermal, nuclear, uranium, turf, etc. any one 7 partial answer e.g.: mention of generator / dynamo / power station /dams (4)

(d) Name one factor on which the potential energy of a body depends 7 or 4 mass / m / weight, height / h, acceleration due to gravity / g any one 7 partial answer e.g. gravity, position, condition (of object),

example of potential energy, etc. (4) (e) What type of energy is associated with wind, waves and moving water? 7

mechanical, kinetic / Ek , renewable 7

(f) Give one disadvantage of non-renewable energy sources 7 or 4 running out / won’t be available for future generations, pollution 7 partial answer (4)

2005 HL Q5(b) State Boyle’s law. (7) pressure is inversely proportional to volume / p α 1/V / pV = k 4 for a definite mass of gas at constant temperature 32005 HL Q6Define (i) angular velocity, (ii) centripetal force. ( 12 )

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(i) ω = θ/t // angle traced out / angular displacement // rate of change 3 correct notation // per unit time / sec // of angle 3 (ii) F = mv2/r or mw2r // force on body in circular motion 3 correct notation // towards the centre (of orbit) 3

It is noticed that the frequency of the received radio signal changes as the satellite orbits Saturn. Explain why. (5) Doppler effect // satellite moves towards (earth) 3 due to relative motion between source (of signal) and detector // and away from earth / detector 2

2005 HL Q12(a)State the principle of conservation of energy. (6) energy cannot be created or destroyed // total energy of an isolated /closed system 3 it can be changed from one form into another // remains constant 3On bouncing from the ground the ball loses 6 joules of energy. What happens to the energy lost by the ball? (4) changes into sound / heat /other forms 4

2004 OL Q6

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Describe an experiment to measure the velocity of a moving object 4 × 3apparatus: trolleytimer / photogate // motion sensorprocedure: measure distance // connect datalogger to sensormeasure time // start programconclusion:

v = st // choose distance versus time graph

any four 4 × 3accept valid alternativesa labelled diagram may merit marksName two forces acting on the cheetah while it is running 2 × 3gravitational / gravity / weightfrictionair resistance / drag(propulsion) force of muscles, etc. any two 2 ×3

2004 OL Q12(a)part (a)Define momentum 2 × 3mass 3(multiplied) by velocity 3p = mv (2 × 3)Give the unit of momentum 3kg m s−1, N s 3State the principle of conservation of momentum 3 × 3momentum before 3equals 3momentum after (in a closed system / when no external force acts) 3m1u1 + m2u2 = m1v1 + m2v2 (3 × 3)(total) momentum is conserved (2 ×3)

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2004 HL Q6Define (i) force, (ii) momentum. (12)force is what causes acceleration / change in v / change in momentum 6( change in speed / direction; F=ma … 3 marks)momentum = mass × velocity (= m × v) 6State Newtons second law of motion.Hence, establish the relationship: force = mass × acceleration. (15)rate of change of momentum is proportional to // formula 3applied force and takes place in the direction of the force // notation (for u, v) 3(no reference to direction … -1)

2004 HL Q12(a)State Newton’s universal law of gravitation. (6)force ∝ product of masses // correct expression 3inversely proportional to distance squared // explain notation 3Centripetal force is required to keep the earth moving around the sun. (10)(i) What provides this centripetal force?gravitational force/pull of the sun (on the earth) 4(ii) In what direction does this centripetal force act?towards the sun / centre (of orbit) 3(iii) Give an expression for centripetal force.

3

2003 OL Q5(b) (when a fixed mass of gas is kept at a constant temperature)the pressure varies inversely with the volume // pV = constant 7partial answer e.g. fixed mass of gas kept at a constant temperature (4)

(c) solar / wind / tidal / hydro / biomass 7partial example e.g. dams (4)

2003 OL Q6

Copy and complete the following statement of Newton’s law 4 × 3force / F 3masses / m 3square of distance / d 2 3distance instead of square of distance (2)any two in the correct order 3

What is meant by the term acceleration due to gravity? 6 or 3

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acceleration of falling objects (due to the earth) // the speeding up of falling objects //speeding up due to weight // speeding up due to the pull of the earth 6partial answer e.g. speeding up / pull of the earth / falls to earth / weight / 9.8 m s-2 / g (3)definition of acceleration (3)Describe how the speed of the stone changes as it reaches its highest point 6 h/mslows / stops 6Why is the acceleration due to gravity on the moon less 5 or 3moon has less mass 5reference to different masses // moon smaller // earth bigger (3)

2003 OL Q12(a)

Part(a)Define the moment of a force 2 × 3force (by) 3(perpendicular) distance (from fulcrum) 3turning effect of a force / Fd (2 × 3)(unit is) N m (3)Explain why the handle on a door is on the opposite side to the hinges 7 or 4larger turning effect / moment (of force) // larger distance (between force and axis) 7partial answer e.g. easier to open (4)

2003 HL Q5

(a) State Hooke’s law.

F = -ks // restoring force is proportional to // force α 4explain notation // displacement // extension 3

(b) What is the relationship between the acceleration due to gravity g and the distance from thecentre of the earth?g is inversely proportional 4distance squared 3

2003 HL Q6Give the difference between vector quantities and scalar quantities andgive one example of each. (8)a vector has a direction 3examples (must indicate vector or scalar) 3 + 2Describe an experiment to find the resultant of two vectors. (18)3 (Newton) balances // 3 weights 6joined by string // joined over pulleys 3adjust until the system is at rest 3read each force / balance 3vector sum of two forces = third force (stated or implied) 3

2003 HL Q12(a)

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Use a diagram to show the forces acting on the skydiver and explain why hereaches a constant speed. (12)weight acting down on diagram 3air resistance / friction / buoyancy acting up on diagram 3resultant force = 0 // air resistance = weight 3therefore acceleration = 0 3

2002 OL Q5(a) force / resists (motion) 7example e.g. applying brakes, rubbing hands together, etc. (7)

2002 OL Q6Define 2(2 3)(i) velocity: rate of change // distance time / speed 3(of) displacement //in particular direction 3correct unit (3)(ii) acceleration: rate of change // change in velocity/speed 3of velocity/speed // per second 3

correct unit (3)Complete 2 3acted on by a/there is a (in correct context) 3(resultant/external) force 3What happens L>W 6climbs/ goes up/ gets higher / accelerates upwards 6What happens T>R 6accelerates/ goes faster 6accelerates merits 1 6 only, if it appears in both what happens, unless qualifiedExplain 3 +2moving (with constant velocity)/ thrown forward/ fall/ /feel lighter 3because no (external) force acts 2

2002 OL Q12(a)Pressure 2 3 + 3force 3(per unit) area 3

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or

(unit is) Pascal/Pa // N m-2 3Instrument 6 or 3bourdon gauge/pressure gauge/manometer/barometer 6gauge/meter (3)Explain 3 3pressure outside // atmosphere (outside) 3greater than // pushing in 3pressure inside/vacuum // no air inside to push out 3

2002 HL Q6State Newton’s 2nd Lawforce is proportional 3rate of change of momentum 3OR F ma

3explain symbols 3Name Law and give statementHooke’s 3restoring force (= to k times) // Extension 3displacement // force / load / weight 3Name and describe motionsimple harmonic / SHM 3a 2 s // acceleration is to 3explain // displacement / distance (and direction) 32 other examplesstretched elastic / pendulum, oscillating magnet, springs of car,vibrating tuning fork, object bobbing in water waves,ball in saucer, etc . or any system that obeys Hook’s lawany two, 2 by 3

2002 HL Q12(a)State principle of conservation of momentummomentum before = momentum after / equation 3no external force 3Directionforward / towards space station / to right 4Change in directiongas expelled in one direction 3rocket in other direction 3

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6th Year Physics: Light Theory

2013 OL Q5(e),(f)

(e) How does light travel through an optical fibre? 7 or 4 (by) total internal reflection stated or shown by diagram 7 partial answer e.g. by reflection (4)

(f) Give a common use for a convex lens. 7 or 4 magnification, (eye) glasses, binoculars, contact lenses, camera, etc. 7 partial answer e.g. use of convex mirror (4)

2013 OL Q12(d)

(b) The diagram shows a beam of white light undergoing refraction and dispersion as it passes through a prism.

(i) What is meant by dispersion? 2×3 splitting/separating of light 3 into colours/frequencies/wavelengths 3 partial answer e.g. refers to different speeds of light / refractive indices (3) (ii) What is observed on the screen between X and Y? 6 or 3 spectrum // different colours 6 partial answer e.g. names two colours (3) (iii) What information does dispersion give about the nature of white light? 4 or 2 it consists of different colours // that it is a wave 4 partial answer e.g. (2) (iv) Give another method for the dispersion of light 6 or 3 (shine light through a) diffraction grating // (reflection from a) CD/DVD/oil 6 partial answer (3) (v) Give an everyday example of the dispersion of light 6 or 3 rainbow, reflection of light from a CD/DVD/oil 6 partial answer (3)

2013 HL 11(a)

(a) Seismic waves can be longitudinal or transverse. What is the main difference between them? direction of vibration parallel to direction of propagation of wave .. (longitudinal) direction of vibration perpendicular to direction of propagation of wave .. (transverse) 4 + 3 (award 7 marks for “only transverse waves can be polarised” )

2013 HL Q12(b)

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(b) A narrow beam of light undergoes dispersion when it passes through either a prism or a diffraction grating. What is meant by dispersion? separation of light 3 into its different colours /frequencies / wavelengths 3 Give two differences between what is observed when a narrow beam of light undergoes dispersion as it passes through a prism, and what is observed when a narrow beam of light undergoes dispersion as it passes through a diffraction grating. red light deviated least in a prism and deviated the most in a grating (or equivalent) 3 many spectra observable with a grating, only one with a prism 3 Give another example of light undergoing dispersion. rainbow, etc. 4 Yellow light of wavelength 589 nm is produced in a low-pressure sodium vapour lamp. What causes the sodium atoms to emit this light? electrons changing energy levels 3

2012 OL Q7

Under certain conditions, light can undergo diffraction and interference. (i) Explain the underlined terms. 2 X ( 6 or 3)

diffraction is the spreading out of waves around a barrier / the edges of an opening // correct diagram 6 partial answer e.g. light spreads out, bending

(3)

interference occurs when two waves meet and add // correct diagram 6 partial answer (3) reversed explanations (6)

(ii) Describe an experiment to demonstrate the wave nature of light 4 X 3apparatus: (light) source, (diffraction) grating / slits, screen three pieces

2 X 3 one piece (3)procedure: shine the (narrow beam of) light through the grating

3 observation/conclusion; pattern on screen 3

incorrect experiment maximum mark 2 X 3 marks may be obtained from a diagram accept valid alternatives

The photograph shows Polaroid sunglasses which reduce glare caused by sunlight. (iii) Explain the term polarisation 6 or 3 polarisation is the restriction of (vibrating electromagnetic) waves to a single plane

6

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marks may be obtained from a diagram partial answer (3)

(iv) Describe an experiment to demonstrate the polarisation of light 4 X 3 apparatus: (two pieces of a) polaroid sheet 3 procedure: look at the light through the two pieces of polaroid

3cross/rotate one of the polaroid pieces

3 observation/conclusion; the crossed pieces stops the light 3 marks may be obtained from a diagram accept valid alternatives (v) What type of wave motion does light have as indicated by the experiment in part (iv)? 9 or 6 or 3 transverse

9 electromagnetic (6) partial answer e.g. refers to longitudinal

(3) (vi) Why are Polaroid sunglasses more effective than non-Polaroid sunglasses at reducing glare? 5 or 3 polaroid sunglasses remove most of the polarised reflected light (which causes the glare) while ordinary sunglasses doesn’t // reflected light is polarised

5 partial answer e.g. reduces intensity (3)

2012 OL Q12(b)

Part (b) State the laws of reflection of light. 2 x 3 the incident ray the normal and the reflected ray are all in the one plane

3 the angle of incidence is equal to the angle of reflection // i = r

3 partial answer e.g. states the laws of refraction

(3) How would you estimate the focal length of a concave mirror? 3 x 3 (reflect image of ) distant object

3 (onto) screen (and adjust screen until the image is sharp)

3 distance from screen to mirror is (approximate) focal length

3 partial answer e.g. 1

f=1

u + 1v // half way between the centre of curvature and pole

(3)

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The diagram shows an object O in front of a concave mirror, whose focus is at F. Copy and complete the diagram to show the formation of the image of the object O 3 x 3

partial answer (3)

Give one use for a concave mirror. 4 or 2 torch / headlights /searchlight, dentist mirror, cosmetic / shaving mirror, solar furnace, (reflecting) telescopes, etc. one correct

4 partial answer e.g. use of a convex mirror / lens

(2)

2012 HL Q5(e)

(e) List three conditions necessary for an observer to see a rainbow.any valid answer: observer’s back to sun / (bright) sunlight /(suspended) droplets of water /proper angleof viewing, etc. Any one condition:

4two additional conditions:

3(any reference to refraction or total reflection, award 4 marks)

2012 HL Q7

The diagram shows a simplified version of the electromagnetic spectrum. Name the sections A and B in the diagram.A: infra red /I.R 3

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B: ultra violet / U.V 3Describe how to detect each of these radiations.A: thermometer (with blackened bulb) / temperature sensor /photographic plate / mobile phone camera/ etc

3effect e.g. rise in temperature 2B: (shine on) Vaseline/detergents / phosphor 2effect e.g. fluorescence / glows 2Distinguish between interference and diffraction.interference:when waves from different sources overlap // when waves superimpose

3a new wave is formed // to form a resultant wave (of greater or lower amplitude)

3(suitable diagram could merit {3 + 3})diffraction:the spreading of a wave // the bending of waves // the spreading of waves

3into the (geometrical) shadow of an obstacle // around obstacles // by passing them through an aperture

3(suitable diagram could merit {3 + 3})Can a diffraction grating which diffracts light also diffract X-rays?no 3Justify your answer.line spacing must be similar to the wavelength of the radiation (for diffraction to occur) /the spacing between lines in (such) a grating is too large (for diffraction to occur) /for x-ray diffraction, gratings in which lines are separated by infinitesimal distances are required 6

Light travels as a transverse wave. Name another type of wave motion.longitudinal 3Give two differences between these two types of wave motion.transverse can be polarized – longitudinal cannot // (medium) vibrates perpendicular to direction wave travels– (medium) vibrates parallel to direction (longitudinal) wave travels

any two 4+4

2011 OL Q5(d) Which one of the following terms is associated with wave motion? 7half-life interference induction doping 7

(f) Give two uses of a concave mirror. 7 or 6 or 4headlights, makeup, shaving mirrors, etc. two correct

7one correct (6)

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partial answer e.g. two uses for a lens (4)

2011 OL Q7

(i) Explain the underlined terms. 2×(6 or 3)reflection is the bouncing of a wave off an obstacle / mirror // correct diagram

6partial answer e.g. light reflects off a mirror (3)refraction is the bending of a wave when it enters a different substance //correct diagram 6partial answer (3)reversed explanations (6)(ii) Give a practical application of the reflection of light. 3mirrors / optic fibres / binoculars, etc 3(iii) State the laws of reflection of light? 9 or 6 or 3angle of incidence is equal to the angle of reflectionincident ray, the normal, and the reflected ray are coplanartwo lines correct 9one line correct (6)partial answer (3)(iv) Explain, with the aid of a diagram how total internal reflection can occur 9 or 6 or 3

correct diagram and explanation 9middle diagram // right hand diagram // correct explanation without diagram

(6)partial answer e.g. left hand diagram (3)(v) What is meant by the ‘critical angle’ in total internal reflection? 6 or 3the angle of incidence above which total internal reflection occurs /the angle of incidence where the angle of refraction is 90º

6partial answer e.g. angle in the more dense medium

(3)

(vi) Draw a diagram to show how light waves travel along an optical fibre. 9 or 6 or 3

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correct diagram to include fibre, indication of two media, multiple reflections 9

one omission (6)partial answer (3)(vii) Give two advantages of using optical fibres instead of copper wires whentransmitting data. 5 or 3cheaper, can carry more signals, faster, less power consumption, etctwo correct 5one correct (3)(viii) Optical fibres are also used in medicine. Give an example of their use in medicine 3endoscope / to look inside body /( keyhole) surgery , etc

3

2011 HL Q5

(c) Why is a convex mirror used, instead of a plane mirror, as a door mirror on a car?wider / greater field of view / any valid answer

7

2011 HL Q12(b)

(b) State the laws of refraction of light.incident ray, refracted ray and normal in same plane

3

A lamp is located centrally at the bottom of a large swimming pool, 1.8 m deep.

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Draw a ray diagram to show where the lamp appears to be, as seen by an observer standing at the edge of the pool. (7)

correct emergent ray 4

image position correctly indicated 3

At night, when the lamp is switched on, a disc of light is seen at the surface of the swimming pool.Explain why the area of water surrounding the disc of light appears dark.(no light emerges from pool due to) total internal reflection / appropriate diagram

3

2010 OL Q5

(d) Which of these scientists is associated with the law of refraction of light? 7Rutherford Snell Joule EinsteinSnell 7

2010 OL Q12(b)

What is meant by dispersion of light? 2 3breaking up of (white) light 3into different colours // into constituent colours 3partial answer (3)Describe an experiment to demonstrate the dispersion of light 4 3apparatus: white light 3prism, (diffraction) grating, CD 3procedure: shine a beam of light at the prism/CD/grating 3observation //conclusion: : different colours / 3 named colours / spectrumwhite light is dispersed // white light consists of different colours 3marks may be obtained from a diagramaccept valid alternativesGive an example of the dispersion of light occurring in nature 4 or 2rainbow / oil film colours / soap bubble colours / CD colours 4partial answer e.g. incomplete answer (2)Only red, green and blue lights are needed to create most lighting effects.Explain why 6 or 3all colours can be made by mixing red, green and blue // primary colours 6partial answer e.g. incomplete answer (3)

2010 HL Q5

(c) Name the parts labelled A and B of the spectrometer shown in the diagram.

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A = (turn)table, B = telescope 4 + 3

2010 HL Q7What is the Doppler effect?(apparent) change in frequency 3due to (relative) motion between source and observer 3Explain, with the aid of labelled diagrams, how this phenomenon occurs.Diagram:labelled moving source of waves ( –1 if no label) 3shorter wavelength approaching observer 3longer wavelength receding 3correct reference to frequency change 3( –1 if waves not clearly indicated /implied)Describe a laboratory experiment to demonstrate the Doppler effect.source of sound (e.g buzzer) 3swing source attached to string 3note frequency change instant source passes observer 3(source may also be propelled longitudinally along a string, etc.)What causes the red shift in the spectrum of a distant star?stars move relative to earth 3(longer λ if) star receding (from earth) 3

The yellow line emitted by a helium discharge tube in the laboratory has a wavelength of 587 nmas shown in the diagram. The same yellow line in the helium spectrum of a star has a measuredwavelength of 590 nm.What can you deduce about the motion of the star?star is receding/moving away from earth 3

Give another application of the Doppler effect.radar, medical imaging, blood flow measurement (echocardiogram), temperature measurement,(underwater) acoustics, etc. 5

2009 Ol Q5

2009 OL Q7In an experiment a beam of monochromatic light passes through a diffraction grating andstrikes a screen.(i) Explain the underlined terms 2(6 or 3)light of one colour / one wavelength 6partial answer; e.g. sodium, laser (3)piece of glass/plastic with lines / slits engraved 6partial answer; e.g. reference to slits (3)marks may be obtained from a diagram(ii) Describe what’s observed on the screen 6 or 3(series of) bright dots 6partial answer (3)

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marks may be obtained from a diagram(iii) Explain, with the aid of a diagram, how this phenomenon occurs 5 + 3 x 3

(iv) What does this experiment tell us about the nature of light? 6 or 3(light has a) wave nature / light is a wave 6partial answer (3)(v) Which property of light can be determined by taking measurementsin this experiment? 6 or 3wavelength / frequency 6partial answer; e.g. velocity/speed (3)(vi) What measurements must be taken to determine the property you named? 2 (6 or 3)angle θ (between bright dots), distance (between slits), n //distance between bright dots, distance from the, screen to grating, distancebetween slits, n two correct 2×6one correct (6)

2009 OL Q11(a) What causes the twinkling of stars? 7 or 4atmospheric turbulence // refraction 7partial answer (4)(b) Give another name for the twinkling of stars 7 or 4stellar scintillation 7partial answer (4)(c) What is meant by the refraction of light? 7 or 4change in direction (as it passes from medium to another ) 7partial answer (4)(d) Name two properties of air that are affected by atmospheric turbulence 7 or 4refractive index, density, temperature two correct 7one correct (4)(e) Why is the air turbulent in towns? 7 or 4heat rising from buildings 7partial answer (4)(f) How can you tell the difference between a planet and a star in the night sky ? 7 or 4planets do not twinkle (stars do) / stars twinkle (planets do not) 7partial answer; e.g. reverse order (4)(g) Why do stars close to the horizon twinkle more? 7 or 4the light (of stars near the horizon) has to travel through more air // refraction is morenoticeable // more refraction 7

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partial answer (4)(h) A star emits light, what is the source of this energy? 7 or 4nuclear / fusion 7partial answer; e.g. mistakes planet for star and refers to the sun (4)

2009 HL Q5(e) Draw a ray diagram to show the formation of an image in a convex mirror.two correct reflected rays 4image behind the mirror 3

2009 HL Q7When light shines on a compact disc it acts as a diffraction grating causing diffraction and dispersion of the light. Explain the underlined terms.spreading (out) of a wave 3when it passes through a gap / by an obstacle 3splitting (up of white) light 3into (its constituent / different) colours 3Derive the diffraction grating formula.diagram showing grating, two rays, angle θ indicated 3(for constructive interference ) path difference = nλ 3path difference = d sin θ 3nλ = d sin θ 3The laser is replaced with a source of white light and a series of spectra are formed on the screen.Explain(i) how the diffraction grating produces a spectrum;different colours 3(have) different wavelengths/frequencies 3constructive interference occurs / bright images formed at different θ 3(ii) why a spectrum is not formed at the central (zero order) image.at central image θ = 0 // constructive interference occurs for allf / λ / colours // path difference zero // ‘all colours meet’, (state/imply) 2

2009 HL Q12(c)Information is transmitted over long distances using optical fib res in which a rayof light is guided along a fibre. Each fibre consists of a core of high quality glasswith a refractive index of 1.55 and is coated with glass of a lower refractive index.Explain, with the aid of a labelled diagram, how a ray of lig ht is guided along a fibre.Diagram:showing light ray in glass fibre 3showing ray being reflected at least once 3(–1 if no label)reference to critical angle/ total internal reflection 3Why is each fibre coated with glass of lower refractive index?ray travelling from denser to rarer medium // so that total internal reflection occurs 3total internal reflection occurs / i > ic // no light escapes 3

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Sunlight is made up of different colours and invisible radiations. (i) How would you show the presence of the different colours in light? 3 ×

3 apparatus: (glass) prism, (light source, slits, screen) // diffraction grating, (light

source) 3 procedure: shine the light through the prism // allow light through the grating

3 observation/conclusion: light spreads out into different colours

3 accept valid alternatives e.g. reflection from CD / oil

(ii) Name two radiations in sunlight that the eye cannot detect. 2 × 3 infra-red / IR

3 ultra-violet / UV 3 (iii) Describe how to detect one of these radiations. 3 × 3 apparatus: thermometer / temperature sensor // fluorescent material / UV sensor

3 procedure: place in IR light // place in UV light source

3 observation / conclusion: temperature rises // material glows / sensor lights

3 (iv) Give a use for this radiation. 4 or 2 heat source, hatch chickens, heat treatment of muscles etc // suntan, forensics

detect forged currency,disco lights, used in insect removal device, sterilisation etc

4 partial answer e.g. use mismatched with description

(2)

2008 HL Q5(d) Why does diffraction not occur when light passes through a window? width of window / gap 4

is too large 3

[“window is too wide (relative to wavelength of light)”, 7 marks] state/imply

(e) Why is a fluorescent tube an efficient source of light? (a relatively) high percentage/most of the (electrical) energy is converted to 4 light (energy) state/imply 3

2008 HL Q9What is meant by refraction of light? bending of light 3 going from one medium to another (of different refractive index) 3 (appropriate diagram showing light ray passing through two different media .. 2 × 3)

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State Snell’s law of refraction. the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant 6

Draw a diagram to show the path of a ray of light as it passes from water of refractive index 1.33 into the cornea. line representing interface between two media 3 straight line (accept a slight refraction) representing the light ray through the two media 3

A swimmer cannot see properly when she opens her eyes underwater. When underwater: (i) why does the cornea not act as a lens?

light not refracted at cornea (state/imply) 3 water and cornea have the same n value 3

(ii) what is the maximum power of the eye? 26 (m–1) / maximum power of the internal lens 3

(iii) why do objects appear blurred? internal lens not powerful enough to focus light on retina / eye is long-sighted / light not brought to a focus (on the retina) 3

(iv) explain how wearing goggles allows objects to be seen clearly. light refracted on passing from air to cornea 3 cornea (now) acts as a lens ( state/imply) 2

2008 HL Q11(d) Name three different electromagnetic radiations.

first type (e.g. x-rays) 4

next two types (e.g. microwaves, ultra-violet) 3

2007 OL Q5(e) The diagram shows parallel rays of light approaching a concave mirror.Copy the diagram and show the paths of the rays after they strike the mirror 7 or 4two correct rays 7partial answer e.g. one ray drawn correct (4)

2007 OL Q8(a)(i) What is meant by the terms dispersion and spectrum? 3 × 3 + 1dispersion – breaking up white lightinto its (constituent) coloursspectrum – the range of colours/wavelengths present in

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the light source / in white light / rainbow / em radiation

four correct 3 × 3 + 1three correct (3 × 3), two correct (2 × 3), one correct (1 × 3)accept spreads out / scatters for breaking up(ii) What happens to the white light when it enters the prism at Z? 6 or 3changes direction / is refracted / slows down / dispersed / broken up 6partial answer (3)

(iii) Name the invisible radiation formed on the screen at (i) region X, (ii) region Y 6 + 3X = infra-red / IRY = ultra-violet / UVtwo correct 6 + 3one correct (6)partial (3)(iv) Describe how to detect one of these invisible radiations 6 + 2 × 3apparatus: blackened thermometer /infra red thermometer // florescent material 6procedure: beyond red // beyond violet 3observation/conclusion: rise in temperature // will fluoresce/glow 3accept valid alternativesa labelled diagram may merit full marks(v) Give a use for one of these invisible radiations 6 or 3infra-red: source of heat, keep things warm, hatch chickens, heat treatmentof muscles etc.ultra-violet: detect forged currency, disco lights, used in insect removaldevice, sterilisation, suntan, forensics, etc.any one 6partial answer (3)

(b)The colour on a TV screen is made by mixing the primary colours.(i) Name the primary colours 6 + 3red, green, blue all three correct 6 + 3any one correct (6)(ii) How is a secondary colour (e.g. yellow) produced on a TV screen? 4mixing two (primary) colours/ mixing red and green (colours) 4accept mixing primary colours

2007 HL Q5(b) Why is a filament light bulb not an efficient source of light?any reference to the production of: heat (energy) 7[ “The output / light energy is only a small percentage / fraction of the input / electrical energy”. 7 marks]

2007 HL Q5(d) How is infra-red radiation detected?thermometer / temperature sensor(or probe) / photographic film(or plate) / (by its) heating effect, etc. (any one) 7

2007 HL Q7What is the Doppler effect?

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apparent change in frequency / wavelength 3due to relative motion between source and observer (state/imply: e.g. either S or O moving) 3Explain, with the aid of labelled diagrams, how this phenomenon occurs.non-concentric circles ( -1 if not labelled as waves ) 3source and direction of motion (stated/implied) 3position of observer indicated 3shorter wavelength / higher frequency on approaching observer (or vice versa) 3The emission line spectrum of a star was analysed using the Doppler effect. Describe how an emission line spectrum is produced.(monatomic) gas (or atoms) 3is heated / is excited /receives energy 3electron(s) move/jump to higher level/state 3electromagnetic radiation/energy/photon/quantum emitted on return 3appropriate diagram may merit full marks ( 4 x 3)Alternatively:(monatomic) gas discharge tube / example, e.g. Na lamp (2 x 3)spectrometer + prism/grating // a direct vision spectroscope // (diffraction) grating (3)observation (e.g. a number of bright lines are seen) (3)

The red line emitted by a hydrogen discharge tube in the laboratory has a wavelength of 656 nm. The same red line in the hydrogen spectrum of a moving star has a wavelength of 720 nm.Is the star approaching the earth? Justify your answer.no 3wavelength has increased // frequency has decreased 5

2006 OL Q5

(f) Give one use of a spectrometer. 7 or 4 measure angles/ measure wavelength of light / demonstrate interference / demonstrate diffraction / demonstrate spectra / chemical analysis, etc. 7 partial answer e.g. spectrometer diagram (4)

2006 OL Q12(b)Part (b) (i) Name the radiations marked A and B. 2 × 3 A = X-rays 3 B = radiowaves / VHF / UHF etc. 3 partial answer e.g. names correct but in the reverse order (3) (ii) Give one property which is common to all electromagnetic radiations. 6 or 3 travel at the speed of light / same speed / can travel through vacuum / diffraction /

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interference / transverse waves / refracted / reflected /forms of energy, etc. any one 6 partial answer e.g. waves (3) (iii) Which one of the radiations has the shortest wavelength? 6 gamma

(iv) Describe how IR radiation is detected. 6 or 3 thermometer / heat sensor / photographic film 6 partial answer e.g. refers to temperature / heat (3) (v) Give one use for microwaves. 4 ovens/cooking, communications /satellite TV / mobile phones / weather radar / missile guidance / remote control / research / speed gun etc. any one 4

2006 HL Q7What is meant by the refraction of light? (6) the bending (of light) 3 on passing from one medium to another 3 (correctly labelled diagram … 2 x 3 )

A converging lens is used as a magnifying glass. Draw a ray diagram to show how an erect image is formed by a magnifying glass. (12) object inside focal point 3 two (appropriate) rays from object to lens 3 two rays emerge correctly from lens 3 rays produced back to form upright virtual image (on same side as object) 3 [ max. of 3 marks if mirror used. -1 if object or image not labelled.]

A diverging lens cannot be used as a magnifying glass. Explain why. (5) diminished image 3 always formed 2

2005 Ol Q5(f) Name two other radiations that are part of the electromagnetic spectrum 7 or 4 radiowaves, microwaves / radar, infrared, (visible) light, ultraviolet, gamma rays, X-rays any two 7 any one of the above or any named light colour (4)

2005 Ol Q7What is meant by the reflection of light? 2 × 3 sending back / returning /bouncing (of light) 3 from a mirror / (shiny) surface 3 a diagram may merit full marks State the laws of reflection of light 6 + 3 incident ray, normal, reflected ray are in the same plane angle of incidence is equal to the angle of reflection // i = r two lines 6+3 one line (6) Describe an experiment to show demonstrate one of the laws of reflection 4 × 3 apparatus: raybox // drawing pins 3 mirror 3

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procedure: mark the position of the rays / pins / measure i and r 3 observation/conclusion: i = r / incident ray, normal and reflected ray in same plane 3 accept valid alternatives a labelled diagram may merit full marks Explain what is meant by refraction 2 × 3 bending /change of direction / velocity (of light waves) 3 at surface / boundary // as it passes from one medium to the other 3 What special name is given to the angle of incidence i ? 6 or 3 critical (angle) / c 6 definition of critical angle without naming it (3)

Draw a diagram to show what happens when i is increased to 45◦ 6 or 3 diagram showing ray reflected at boundary 6 partial answer (3)

Give one application of the effect 5 or 3 optic fibres / telecommunications, binoculars / periscope, medicine / endoscope / correct specific ornament /correct specific toy, etc. any one 5 partial answer e.g. toys, ornaments, prisms, phones, situation where refraction occurs (3)

2005 HL Q7A student used a laser, as shown, to demonstrate that light is a wave motion. (i) Name the two phenomena that occur when light passes through the pair of narrow slits. (6) diffraction 3 interference 3 (ii) A pattern is formed on the screen. Explain how the pattern is formed. (12) slits act as coherent sources 3 waves overlap / meet / path difference between waves (or shown on diagram ) 3 constructive interference gives brightness / bright lines / bright fringes 3 destructive interference gives darkness / dark lines / dark fringes 3 (iii) What is the effect on the pattern when (a) the wavelength of the light is increased. ( 4) distance between fringes / lines / spots increases // pattern more spread out 4 (b) the distance between the slits is increased. ( 4) distance between fringes / lines / spots decreases // pattern less spread out 4

Describe an experiment to demonstrate that sound is also a wave motion. (12) two loudspeakers connected to signal generator // rotate vibrating (tuning) fork 3 walk in front of and parallel to speakers // near ear 3

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observation: (e.g. sound loud and low / waxes and wanes) 3 conclusion: interference occurs showing that sound is a wave motion 3

Sound travels as longitudinal waves while light travels as transverse waves. Explain the difference between longitudinal and transverse waves. (9) longitudinal waves: the direction of the vibrations (of medium) 3 is parallel to the direction of (propagation) of the wave 3 transverse wave: the direction (of the vibrations) is perpendicular to the (direction of the) wave 3

Describe an experiment to demonstrate that light waves are transverse waves. (9) light source and two pieces of polaroid 3 rotate one polaroid relative to the other and light (intensity)decreases (to zero) 3 polarization indicates transverse waves 3

2004 OL Q5(a) Draw a diagram to show how a ray of light is transmitted throughan optical fibre 7 or 4incident ray in fibrereflected ray in fibre two correct 7one correct / no fibre shown (4)(b) How is the escape of light from the sides of an optical fibre prevented? 7 or 4cladding/coating with glass/plastic (of lower/different refractive index),because of total internal reflection 7partial answer (4)(c) Name a material that is used in the manufacture of optical fibres. 7glass / plastic / sand / silicon 7(d) What is the bending of light as it moves from one medium to another called? 7refraction / refracted 7(e) What is meant by the refractive index of a material? 7 or 4// ability to refract / bend light 7partial answer e.g. one error in equation (4)(f) Define the critical angle. 4 + 3angle in denser mediumthat gives angle of refraction of 900 two correct 7one correct (4)partial answer e.g. depends on the refractive index / where t.i.r. occurs (4)a labelled diagram may merit full marks(g) When will total internal reflection occur? 4 + 3when angle of incidence is greaterthan critical angle two correct 7one correct (4)partial answer e.g. when using optical fibres (4)(h) Give one use for optical fibres 7 or 4endoscope, telecommunications, binoculars, correct specific ornament/toy,to supply light to inaccessible places, etc.any one 7partial answer e.g. ornaments, toys (4)

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2004 OL Q11Give one difference between a real image and a virtual image 6a real image can be obtained on a screen / a virtual image cannot, in a real imagethe light rays meet / in a virtual image they do not, a real image is always inverted/a virtual is erect, a real image is in front / a virtual image is behind, etc. 6Use a ray diagram to show the formation of a real image by a concave mirror 2 × 3one ray reflected correctly 3second ray reflected correctly 3Give two uses for a concave mirror 2 × 3torch / headlights /searchlight, dentist mirror, cosmetic / shaving mirror,solar furnace, (reflecting) telescopes, etc. any two 2 × 3

2004 OL Q12(b)

Give one difference between a real image and a virtual image 6a real image can be obtained on a screen / a virtual image cannot, in a real imagethe light rays meet / in a virtual image they do not, a real image is always inverted/a virtual is erect, a real image is in front / a virtual image is behind, etc. 6Use a ray diagram to show the formation of a real image by a concave mirror 2 × 3one ray reflected correctly 3second ray reflected correctly 3How far from the mirror will the image be formed? 3 × 3 + 1Equation method Diagram methodleft hand side of equation substituted correctly // focus shown at 20 cm 3right hand side of equation substituted correctly // object shown at 30 cm 3correct rearrangement // image near 60 cm 3calculation // done on graph paper 1v = 60 (cm) (10)Give two uses for a concave mirror 2 × 3torch / headlights /searchlight, dentist mirror, cosmetic / shaving mirror,solar furnace, (reflecting) telescopes, etc. any two 2 × 3

2004 HL Q5

(f) What is meant by polarisation of waves? (7)vibrations (confined to) 4one plane (only) 3(diagram showing polarised and unpolarised concept ... 7)

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2004 HL Q12(b)Give two reasons why the telecommunications industry uses optical fibres instead of copper conductors to transmit signals. (6)less interference / boosted less often / cheaper raw material / occupy less space /more information (carried) in the same space / flexible for inaccessible places/do not corrode, etc. any two 3+3

Explain how a signal is transmitted along an optical fibre. An optical fibre has an outerless dense layer of glass. What is the role of this layer of glass? (13)light ray/signal introduced at one end of fibre; … (stated or implied) 3strikes interface/boundary at i > ic 3total internal reflection occurs 3( -1 if no reference to light)signal/light (then always) remains in denser medium / t.i.r. occurs / prevents lightpassing from one fibre to an adjacent one / prevents light escaping / preventsdamage to surface of the core, etc. 4

2003 OL Q5(f) light waves are transverse // sound waves are longitudinal 7light waves can be polarised // sound waves cannot be polarised (7)light waves travel through vacuum // sound waves cannot travel throughvacuum (7)light waves travel (much) faster in air // sound waves travel slower in air (7)light waves are electromagnetic // sound waves are not electromagnetic (7)light waves have a shorter wavelength // sound waves have a longer wavelength (7)valid example e.g. lightning is seen before thunder is heard (7)partial answer e.g. sound travels around corners // incorrect converse (4)

(g) virtual / behind the mirror, magnified, erect any two 7any one (4)diagram may merit full marks

2003 OL Q7State the laws of refraction of light 2(2 × 3)the incident ray / angle, the normal and the refracted ray 3(are all in the) same plane 3

the sine of the angle of incidence / Sin i 3is proportional to the sine of the angle of refraction 3

law of reflection, maximum mark 2 × 3a labelled diagram may merit marks

Explain, with the aid of a labelled diagram

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(i) total internal reflection, (ii) critical angle 2(2 × 3)

(i) total internal reflection occurs when the angle of incidence (in the more densemedium) is greater than the critical angle 3and light is reflected back (into the more dense medium at the boundary) 3(ii) critical angle is the angle of incidence in the more dense medium 3which causes an angle of refraction of 907 (in the less dense medium) / abovewhich total internal reflection occurs 3a labelled diagram may merit all of the marks

Copy the diagram and show the path of the ray 3 × 3

first correct ray 3second correct ray 3third correct ray 3

Explain why the ray follows the path that you have shown 6 or 3reference to total internal reflection in context 6explanation consistent with an incorrect diagram (2 × 3)partial answer (3)Give two uses of total internal reflection 2 × 4telecommunications / fibre optics, medicine / endoscope, reflective road signs,(prism) reflectors any two 2 × 4

2003 OL Q12(b)Name two primary colours 2 × 3red, green, blue any two 2 × 3one correct (3)What are complementary colours? 2 × 3primary and secondary (colour) // two (colours) 3(when mixed give) white light 3valid example e.g. blue and yellow (2 × 3)

Describe an experiment to demonstrate that white light is made up of light of

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different colours 3 × 3apparatus (white)light source,(slit), prism, (screen) // CD // Newton’s disc 3procedure shine light through the prism // (white) light // rotate 3observation (seven different) colours on the screen // colours // white 3mixing the three primary colour lights // diffraction grating method fits the schemea labelled diagram may merit full marksCopy this diagram and indicate on it the positions of the following 7 or 5 or 3

all four correct 7any two correct (5)any one correct (3)

2002 OL Q5

2002 OL Q7Explain 2(6 + 3)(refraction is the) bending/changing direction/change of velocity of waves 6at the boundary/surface/ (when waves) travel from one medium to another 3accept light/sound for wavesa labelled diagram or correct example may merit marks

(diffraction is the) spreading out of waves/light/sound 6at the other side / at an obstacle/opening 3a labelled diagram or correct example may merit marks

Describe 4 3apparatus: (white light) source, obstacle with a slit, prism/(diffraction) gratingany two 2 3method: shine the (narrow beam of) light through the prism/grating 3observation: (the white) light is split into (seven) colours 3a labelled diagram may merit marksName 6 h/mrefraction, diffraction, polarisation, interference, same speed, reflection,transverse (waves), can travel through vacuum any one 6

Describe 2 3apparatus: (blackened) thermometer (bulb)/thermopile/infrared camera/night

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vision binoculars, etc. 3method: the temperature rises/picture shows ( presence of infrared)/etc. 3a labelled diagram may merit marksUses 6 + 2radar, (mobile) phones, speed trap, (microwave) oven/cooking/defrosting any one 6any other 2

2002 HL Q7Explain the terms (i) constructive interference2 waves combine 3wave of greater amplitude 3(ii) coherentsame frequency / wavelength 3in phase / constant phase difference 3

Condition for destructive interferenceout of phase / path difference // trough meets 3

by λ2 wavelength // crest / peak 3

Wave nature of lightdiffraction grating / Young’s slits // 2 polaroids 3spectrometer and light source / laser // light source 3shine light through grating or slits // shine light, rotate one 3interference pattern // change in intensity 3

2002 HL Q12(b)Laws of refractionincident ray, refracted ray and normal in same plane 3Sin i/ Sin r is a constant 3Optical structure of eyeshape of eye 3(labelled) lens 3labelled retina 3How does eye focus objectschange shape of lens / accommodation 3changes focal length / focus / power 3

6th Year Physics: Sound Theory

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2013 OL Q5(d)

(d) What is meant by the threshold of hearing? 7 or 4 minimum sound (intensity) audible // quietest sound that can be heard 7 partial answer (4)

2013 OL Q6

(a) What is meant by the frequency of a wave? 6 or 3 number of waves per second 6 partial answer e.g. number of waves (3) Give the relationship between the frequency and the wavelength of a wave. 6 or 3 c = fλ // f and λ inversely proportional 6 partial answer e.g. f λ (3) The diagram shows a student walking in front of two loudspeakers along the path between A and B.

A signal generator set at 500 Hz is connected to the loudspeakers.

(i) What will the student notice as he moves from A to B? 6 or 3 loudness varies // increasing and decreasing sound 6 partial answer e.g. frequency varies (3) (ii) Name this phenomenon 4 or 2 Interference 4 partial answer (2) (iii) Explain with the aid of a diagram how this phenomenon occurs. 6 + 3

full marks may be obtained from a diagram 6 + 3 correct explanation alone e.g. two waves (crests/troughs/curves) meet and add (6) partial answer e.g. example of interference (3) (iv) Why should this phenomenon be taken into account in the placing of speakers in theatres or auditoriums? 6 or 3 to ensure that all areas have equal loudness 6 partial answer (3)

(b) The note produced by a guitar string depends on the fundamental frequency of the string. The quality of the note depends on the number of overtones produced.(i) Explain the underlined terms 6 + 3 The loudness of a note is increased by resonance in the body of a guitar. fundamental frequency is the

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lowest / main frequency of an object overtones are multiples of fundamental // higher frequencies produced // harmonics two terms correct 6 + 3 one term correct (6) partial answer (3) (ii) How can the note produced by a guitar string be changed? 4 or 2 change tension / (effective) length / amplitude 4 partial answer (2) (iii) What is resonance? 2×3 transfer of energy 3 between two objects of similar natural frequency 3

2013 HL Q7

What is meant by the term resonance? transfer of energy between two systems (stated or implied) 3 of similar natural frequencies 3 How would resonance be demonstrated in the laboratory? apparatus (e.g. Barton’s pendulums // column of air and tuning fork) 3 procedure (e.g. set one pendulum oscillating // hold vibrating fork over column of air etc.) 3 observation 3

A set of wind chimes, as shown in the diagram, is made from different lengths of hollow metal tubing that are open at both ends. When the wind blows, the wind chimes are struck by a clapper and emit sounds. The sound from one of the tubes was analysed. The following frequencies were identified in the sound: 550 Hz, 1100 Hz and 1651 Hz. What name is given to this set of frequencies? overtones / harmonics 5 Draw labelled diagrams to show how the tube produces each of these frequencies. 550 Hz (f): antinodes (A) at both ends 3 linked correctly to one node (N) (in the centre) 3 1100 Hz (2f): antinodes at both ends 3 linked correctly to two nodes 3 1651 Hz (3f): antinodes at both ends linked correctly to three nodes 3 ( –1 if no correct label)

2012 OL Q5(d)

(d) The Tacoma Narrows Bridge collapsed, soon after construction, due to resonance. What is resonance? 7 or 4 (the tendency of a body to oscillate at a) greater amplitude at some (forced) frequencies // refers to energy transfer at certain frequencies

7 partial answer e.g. refers to natural frequency, valid example

(4) 2012 OL Q12(c)

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Part (c) The pitch of the sound emitted by the siren of a moving fire engine appears to change as it passes a stationary observer. (i) Name this phenomenon. 6 or 3 Doppler effect 6 partial answer (3) (ii) Explain, with the aid of a diagram, how this phenomenon occurs. 4X 3

diagram to show; moving wave source 3

wave fronts 3 as the moving wave source approaches the waves get closer together

2X 3 // conversely as the wave source moves away the waves are further apart accept valid alternatives a labelled diagram may merit full marks partial answer (3)no diagram maximum mark 3 X 3 (iii) Will the crew in the fire engine notice this phenomenon? Give a reason for your answer. 4 or 2 no as there is no relative motion between the sound source and the crew 4 partial answer e.g. no (2) (iv) Give an application of this phenomenon. 6 or 3 measuring speed / speed gun, (measuring) red shift, ultrasonic scanners, imaging used to study blood flow, used to study heartbeat, weather forecasting, etc.

6 partial answer e.g. general application such as medicine, radar, sonar

(3)

2011 OL Q12(b)

(b) Loudness, pitch and quality are characteristics of a musical note.Name the physical property of the sound wave on which each characteristic depends.6 + 2 X 3loudness depends on amplitude / frequencypitch depends on frequencyquality depends on overtones / harmonics

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three correct 6 + 2 × 3two correct (6 + 3)any one correct (6)

A bat detector allows us to hear the sounds emitted by bats. The detector is neededas humans cannot hear the sounds emitted by bats as they are outside thefrequency limits of audibility.(i) What is meant by the frequency limits of audibility? 6 or 3are the lowest and highest frequencies which humans can hear //range of frequencies which we can hear // 20 – 20 000 Hz 6partial answer e.g. incomplete statement / 20 Hz

(3)

(ii) What name is given to a sound whose frequency is greater than ourupper frequency limit of audibility 4 or 2ultrasonic 4partial answer e.g. incomplete statement / supersonic

(2)

2011 HL Q5(d)

(d) What causes the Doppler effect?(relative) motion 4between source (of waves) and observer

3(definition of effect…… 7 marks)

2011 HL Q8

(a) Destructive interference can occur when waves from coherent sources meet. Explain the underlined term.same frequency/wavelength 3in phase / constant phase difference 3Give two other conditions necessary for total destructive interference to occur.same amplitude 4

The diagram shows a standing wave in a pipe closed at one end. The length of the pipe is 90 cm.(i) Name the points on the wave labelled P and Q.P: node Q: antinode 3+3The clarinet is a wind instrument based on a pipe that is closed at one end.What type of harmonics is produced by a clarinet?odd (multiples of the fundamental) 3

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2010 OL Q5

(f) Give one difference between a light wave and a sound wave 7 or 4(light waves) travel faster (than sound waves)// light travels in transverse waves //sound in longitudinal waves // etc. 7partial answer e.g. difference stated but in reverse order (4)

2010 OL Q7

The diagram shows a waveform.(i) What is the name given to the distance (a) X, (b) Y? 2 3X = Wavelength / λ 3Y = Amplitude /height /depth 3partial mark if both correct but reversed (3)(ii) What is meant by the frequency of a wave? 6 or 3number of waves (passing a point) per second 6partial answer (3)(iii) Explain the term natural frequency? 6 or 3frequency objects tends to vibrate at (when set in motion) // resonance frequency 6partial answer e.g. lowest frequency (3)

(v) State the wave property on which (c) the loudness, (d) the pitch, of amusical note depends 3 3(c) (loudness depends on) amplitude / energy // frequency(d) (pitch depends on ) frequency / wavelengthtwo lines correct 3 3one line correct (2 3)partial answer e.g. other property (3)An opera singer, singing a high pitched note, can shatter a glass. Explain why. 6 or 3resonance // transfer of energy 6partial answerDescribe a laboratory experiment to demonstrate resonance 4 3 + 2apparatus: Barton’s pendulums // tuning fork and adjustable length of air 3procedure: hang the pendulums (vertically) from a horizontal string //hold the vibrating tuning fork near air column 3set one of the pendulums swinging // adjust the length of the air column 3observation: the pendulum of the same length also swings //at a certain length the note emitted by the tuning fork gets louder 3conclusion: a transfer of energy occurs / resonance occurs 2marks may be obtained from a diagramaccept valid alternatives

2010 HL Q11

(a) Give two properties of radio waves.travel at speed of light; electromagnetic radiation; travel through vacuum;(can be) reflected; refracted; polarized; etc. any two: 4+3

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(c) What happens to the radio frequency energy absorbed by the body?converted into heat 4carried away by the body 3

(d) Why are radio frequency waves not very penetrating?low frequency / long wavelength / low energy 7

(e) A mobile phone converts the received radio frequency waves to sound waves.What are the audible frequency limits for sound waves?(lower value ≈) 20 Hz 4(upper value ≈) 20 000 Hz (–1 for omission of or incorrect units) 3

(f ) Give two safety precautions you should take when using a mobile phone.keep phone at distance / use loudspeaker function / ‘no hands etc.:brief calls only: direct antenna away from your head: etc. any two: 4+3

(h) Name an electromagnetic wave which may induce cancer. Justify your answer.γ rays / X-rays / UV any one: 4ionization of (body) cells 3

2010 HL Q12(c)Explain the term resonance and describe a laboratory experiment to demonstrate it.transfer of energy (state/imply) 3so that a body vibrates at its natural frequency 3Exemplar:apparatus: tuning fork, length of pipe (with means of varying length) 3procedure: hold vibrating fork over (open) end of pipe and vary length (of air column) 3observation: loud sound is heard (at certain length) 3

Give two characteristics of a musical note and name the physical property onwhich each characteristic depends.Pitch frequencyLoud amplitude / intensity 3×3quality/timbre harmonics / overtones(award 3 marks for each of two ‘characteristics’and a further 3 marks if the associated properties are correct for both)

Explain why a musical tune does not sound the same when played on different instruments.different instruments emit (a fundamental frequency plus) different (combinations of)overtones/harmonics 4(‘a closed pipe emits odd multiples of a fundamental frequency whereas an open pipeemits all multiples of the fundamental frequency’…. 4 marks)

2009 OL Q5(f) On what property does the pitch of a musical note depend ? 7 or 4frequency / wavelength 7partial answer; e.g. loudness, pressure, temperature (4)

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2008 OL Q5(d) What physical quantity is measured in decibels? 7 or 4 sound (level) / intensity 7 partial answer e.g. loudness (4)

2008 Ol Q8The diagram shows a signal generator connected to two loudspeakers emitting the same note. A person walks slowly along the line AB 3(7 or 4) (i) What will the person notice? 7 or 4 sound gets loud and weak ( as they move from A to B) 7

partial answer e.g. sound gets loud (4)

(ii) Why does this effect occur? 7 or 4 any mention of interference 7 partial answer (4) (iii) What does this tell us about sound? 7 or 4 wave (motion) 7partial answer (4) Describe an experiment to demonstrate that sound requires a medium to travel 4×3 + 2apparatus: bell jar with electric bell, battery, vacuum pump two correct 2×3 procedure: turn on pump 3 observation/conclusion: no sound heard when air removed / sound needs a medium 3 detail 2

The pitch of a note emitted by the siren of a fast moving ambulance appears to change as it passes a stationary observer. 3(7 or 4) (i) Name this phenomenon 7 or 4 Doppler effect 7

partial answer e.g. frequency change (4)

(ii) Explain how this phenomenon occurs 7 or 4as sound source approaches (waves closer together) // sound source moves awayhence wavelength shorter / frequency higher // λ longer / f lower

two lines correct 7

one line correct (4)

suitable diagram(s) may merit full marks (7)

(iii) Give an application of this phenomenon 7 or4measuring speed / speed gun, (measuring) red shift, ultrasonicscanners, radar, used to study blood flow, used to study heart

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beat, etc.one correct 7partial answer e.g. example of Doppler effect (4)

2008 HL Q5

2008 Hl Q12(b)(b) The pitch of a musical note depends on its frequency. On what does (i) the quality, (ii) the loudness, of a musical note depend? (i) (number or relative strengths of) overtones /harmonics // wave form 3 (ii) amplitude / frequency/ λ / intensity / rate at which (acoustic) energy enters ear 3 What is the Doppler effect? (apparent) change in frequency 3 due to relative motion (stated or implied) between source and observer 3 Give an application of the Doppler effect. calculate speeds of stars or galaxies / reference to red (or blue) shift / radar / speed traps / etc. 4

2007 OL Q5(f) Give one application of the Doppler effect 7 or 4red shift of stars / speed detection / specific medical use / valid example, etc. 7partial answer e.g. used in hospitals (4)

2007 OL Q7Explain resonance and natural frequency 4 × 3resonance rapid amplification when forced vibration is // transfer of energy 3at natural frequency 3partial e.g. incomplete answer / example (3)a labelled diagram may merit full marksnatural frequency frequency that a body oscillates at // fundamental frequency 3(when) placed into motion / vibrates freely 3partial e.g. incomplete answer / example (3)a labelled diagram may merit full marksDescribe an experiment to demonstrate resonance 4 × 3apparatus: tube of air, tuning fork, means of varying the length any two 2×3any one (3)procedure: hold vibrating tuning fork near the opening and vary tube length 3observation/conclusion: sound amplification 3accept valid alternatives e.g. sonometer, two tuning forks of the same frequency, etc.a labelled diagram may merit full marksWhat is the name given to (i) the distance A (ii) the height B? 6 + 3A = wavelengthB = amplitude / intensity two correct 6 + 3

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any one (6)partial answer e.g. frequency, loudness (3)Explain what is meant by the frequency of a wave 2 × 3number of waves 3(emitted/produced/passing a point) per second 3partial answer (3)State the wave property on which (i) the loudness, (ii) the pitch, of a note depends 2 × 4(i) (loudness depends on) amplitude // frequency / wavelength 4(ii) (pitch depends on ) frequency / wavelength 4

2007 HL Q12(b)(b) Define sound intensity.energy per sec / power / watt // P /A 3per unit area / m-2 // correct notation 3The human ear is more sensitive to certain frequencies of sound. How is this taken into account when measuring sound intensity levels?dBA / decibel adapted / a frequency weighted scale is used// sound level meter (modified so that it) responds more to sounds between 2kHz and 4 kHz / just like the earany one 4

2006 OL Q8Describe, using diagrams, the difference between transverse waves and longitudinal waves. 2(6 or 3) property e.g. transverse waves vibrate perpendicular to the direction of motion / transverse waves may be polarised / longitudinal waves cannot be polarised / longitudinal waves vibrate parallel to the direction of motion 6 partial answer e.g. can travel through vacuum (3) description e.g. diagram / converse of stated property 6 partial answer (3) a labelled diagram may merit full marks The speed of sound depends on the medium through which the sound is travelling. Explain how sound travels through a medium. 6 + 3 energy / vibrations // waves 6 transferred from particle to particle // longitudinal 3 partial answer (3) a labelled diagram may merit full marks Describe an experiment to demonstrate that sound requires a medium to travel 5 × 3 apparatus: sealed container / jar 3 sound source / bell 3 pump 3 procedure: pump out the air 3 observation/conclusion: loudness decreases as air is removed 3 accept valid alternatives a labelled diagram may merit full marks Why is the speed of sound greater in water than in air? 5 or 3 particles are closer together / greater density 5 partial answer e.g. reference to density / better conductor of sound (3)

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2006 HL Q5(d) A sound wave is diffracted as it passes through a doorway but a light wave is not. Explain why. 7 wavelength of light (much) less than wavelength of sound 7

(e) What is the Doppler effect? (7) (apparent) change in frequency (of a wave) 4 any reference to motion (of S or O or both) 3

2006 HL Q11(a) How does resonance occur in an acoustic guitar? (7) energy is transferred from strings to hollow body / sound box /air within 4 both vibrate at the same frequency 3 (b) What is the relationship between frequency and tension for a stretched string? (7) frequency proportional to / f α 4 square root of tension / √ T 3

2005 OL Q12(b)What is meant by (i) diffraction (ii) interference, of a wave? 2(2 × 3) What is meant by (i) diffraction, of a wave? (2 × 3) spreading out (of a wave) 3 around an obstacle / gap / slit 3 bending waves around corners (2 × 3) a labelled diagram or correct example may merit marks What is meant by (ii) interference, of a wave? 2 × 3 (waves) meet 3 add, change in amplitude, greater amplitude / constructive, lesser amplitude / destructive any one 3 labelled diagram or correct example may merit marks Describe what the person hears 2 × 3 loudness 3 varies, increasing and decreasing, changing any one 3 What does this experiment demonstrate about the nature of sound? 6 or 3 (sound is a) wave 6 partial answer e.g. interference (3) What is meant by the amplitude of a wave? 4 height, accept loudness 42005 HL Q12(c)The frequency of a stretched string depends on its length. Give two other factors that affect the frequency of a stretched string. (6) tension 3 mass per unit length / mass per metre / linear density 3

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2005 OL Q5(c) Give one application of the Doppler effect 7 or 4measuring speed / speed gun, (measuring) red shift, ultrasonic scanners,used to study blood flow, used to study heart beat, etc. any correct application 7partial answer e.g. example of Doppler effect 4

(d) Name two primary colours of light 7 or 4red, blue, green any two 7any one (4)

(e) Which one of the following is not part of the electromagnetic spectrum? 7sound waves 7

2004 OL Q8Explain diffraction 2 × 3spreading out (of a wave) 3around an obstacle / opening 3bending of waves around corners (2 × 3)labelled diagram or correct example may merit marksExplain interference 2 × 3waves meeting 3add / change in amplitude / displacement 3labelled diagram or correct example may merit marksDescribe an experiment to demonstrate the interference of sound 6 + 3 + 2apparatus: two sources e.g. two loudspeakers // tuning fork 6procedure: walk between speakers // rotate (vibrating) tuning fork (near ear) 3observation/conclusion: observed sound varies in loudness 2labelled diagram may merit marksaccept valid alternativesWhat is the name given to the points on the string marked 6 + 3(i) X = node / null (point) (ii) Y = antinode two correct 6 + 3correct names mismatched / one correct (6)partial answer e.g. crest/trough (3)How many wavelengths are contained in the distance marked L? 6 or 3two 6four (3)State two factors on which the natural frequency of a stretched string depends 6 + 3length / ltension / Tthickness / mass per unit length / (linear density) / cross-sectional area / radius / μmaterial any two 6 + 3any one (6)

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2003 HL Q5

(d) Which wave phenomenon can be used to distinguish between transverse waves andlongitudinal waves?polarisation 7

(e) Sound intensity level can be measured in dB or dB(A). What is the difference between thetwo scales?idea of dB(A) being adapted to human ear 4frequency 3

2003 HL Q7

Describe an experiment to show that sound is a wave motion. (12)tuning fork // 2 speakers // microphone and CRO 3set vibrating //attach to same frequency source // sound source 3rotate by ear // walk in front of speakers // observe pattern on screen 3increase and decrease of sound // wave pattern 3What is the Doppler effect? Explain, with the aid of labelled diagrams, how thisphenomenon occurs. (14)change in frequency 3motion of source / observer 3non concentric circles, stated or implied as waves 3close parts of circles show high frequency / short wavelength 3centres show direction of movement of source 2

Give two other applications of the Doppler effect. (6)speed traps / speed of stars (red shift) / landing aircraft/ ultrasound (blood movement or heartbeat of foetus) /measure temperature / weather forecasting. 4 + 2

2002 OL Q5

(e) sound (intensity level) 7partial answer (4)

(h) complete example e.g. pitch of moving sound source changes as it goes past 7definition/incomplete example e.g. when a car passes by, (4)

2002 HL Q5(d) change in frequency / pitch /wavelength 4Movement 3

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6th Year Physics: Heat Theory

2013 OL Q9

When heat is transferred to or from an object the temperature of the object changes. (i) What is heat? 6 or 3 (a form of) energy / mcΔθ /ml 6 partial answer e.g. J (3) (ii) Name the three ways in which heat can be transferred. 3×3 conduction 3 convection 3 radiation 3 partial answer e.g. (3) (iii) Describe an experiment to show how heat is transferred in a liquid 3×3 apparatus; liquid in glass beaker, heat source, (solid) dye any two 3 procedure; put the dye in the liquid and heat 3 observation/conclusion; the dye can be seen rising to the top of the liquid / convection currents visible 3 full marks may be obtained from diagrams accept valid alternatives partial answer e.g. incomplete description (3) incorrect experiment maximum mark 2 × 3

The water in an electric kettle is heated by the element and its handle is made from an insulating material (iv) How does the method of heat transfer in a liquid affect the positioning of the heating element in a kettle? 6 or 3 heating element at the bottom of the kettle 6partial answer e.g. incomplete answer (3) (v) Why is the handle of a kettle made of an insulating material? 4 or 2 insulator doesn’t conduct heat // safe to touch 4 partial answer e.g. incomplete answer (2) (vi) Name an insulator suitable for use in the handle of a kettle. 4 or 2 any suitable insulator e.g. plastic, wood, ceramic, etc. 4 partial answer e.g. incomplete answer (2)

2013 HL Q5(c) (d)

(c) Explain why heat does not travel through solids by means of convection. the particles cannot move (freely) 7

(d) Storage heaters are frequently used to heat buildings. State the principle that underlies the operation of an electrical storage heater. large heat capacity 4 heated when electricity is inexpensive (off peak) / store a large quantity of energy / release energy slowly (during the day) (any one) 3

2013 HL Q12(d)

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(d) What is meant by the term thermometric property? (physical) property that changes (measurably) 3 with temperature 3

This graph was obtained during an experiment where the resistance R of a thermistor was measured as its temperature θ was raised from 0 °C to 100 °C (as measured by a mercury-in-glass thermometer). The thermistor is used in a circuit to keep the water in a tank at a constant temperature. Why do the thermistor and the thermocouple thermometer give different temperature readings for the water in the tank? each of the devices has a different thermometric property that changes differently with temperature 4 + 3

2012 OL Q5(e)

(e) A building has a low U-value. What is the advantage of this? 7 or 4 low energy loss, etc.

7 partial answer

(4)

2012 OL Q9

The temperature of an object is a measure of its hotness or coldness. (i) What is the SI unit of temperature? 6 or 3 K 6 partial answer (3) (ii) The Celsius scale is the practical temperature scale. How is the degree Celsius (°C) related to the SI unit of temperature? 6 or 3

When heat is transferred to a substance, it causes a rise in temperature or a change in state of the substance, or both. (iii) What is heat? 6 or 3 (a form of) energy / mc∆ θ /ml 6 partial answer (3) (iv) Name the three methods of heat transfer. 6 or 3 conduction, convection, radiation 6 partial answer e.g. incomplete answer (3) (v) What is meant by the change in state of a substance? 3 any change between solid, liquid or gas

3 (vi) Define specific latent heat. 6 or 3 (amount of )energy required to change 1 kg of the substance from one state to another (without a change in temperature) 6 partial answer e.g. incomplete answer (3)

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2012 HL Q5

(f) How is energy transferred from the sun to the earth?(by means of) radiation / photons / electromagnetic waves

7(g) A person smokes a cigarette at the entrance to a building. Explain how a significant amount of the smoke from the cigarette can enter the building.(reference to) convection currents / diffusion / wind assisted / pressure variations, etc. 72012 HL Q12(c)

(c) The graph shows the variation in temperature θ of 150 g of crushed icewhen it was supplied with energy ∆E at a constant rate.

(i) Explain the shape of the graph.temperature of ice increased (from ≈ –3oC to 0oC as energy is added)

3ice temperature stays at 0oC while ice is melting / changing state

3reference to latent heat

3(once melted) ice melt /water temperature increases (to 1oC)

3(ii) Describe how energy could have been supplied at a constant rate.(heating) coil/element

3

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joulemeter / ammeter + rheostat 3

(water bath … 6 marks; hotplate …3 marks)

2011 OL Q5(e)

(e) Name the three ways by which heat can travel from one place to another. 7 or 4conduction, convection, radiation three correct

7partial answer e.g. metal one correct

(4)

2011 OL Q8(a) (i) What is meant by a thermometric property? 6 or 3a property that changes with temperature /heat (change)

6partial answer

(3)(ii) Name two different thermometric properties. 6 or 5 or 3length of mercury column, colour, E, V, R , etc.two correct 6one correct (5)partial answer e.g. mercury and alcohol

(3)(iii) Name two different thermometers 2 x 2mercury, alcohol, thermocouple/thermopile, pyrometer, resistance,constant volume gas, digital thermometer, etc.two correct 2 x 2one correct (2)(iv) Describe how to calibrate a thermometer. 4 x 3apparatus: container of water, heat source, un-calibrated thermometercalibrated thermometer, marker three pieces

2 x 3one piece (3)procedure: place the thermometers in water, heat to different temperatures

3and mark / plot calibration curve

3marks may be obtained from a diagramvalid alternatives(v) Why is there a need for a standard thermometer? 6 or 3because different thermometric properties give different results //thermometers respond differently // to ensure a consistent measure //for calibration, etc.

6

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partial answer e.g. accuracy (3)

(b) An electric kettle is filled with 500 g of water and is initially at atemperature of 15 oC. The kettle has a power rating of 2 kW.(iv) Name a suitable material for the handle of the kettle. Justify your answer. 2 x 2plastic / wood

2good insulators / will not burn hand

2

2011 HL Q7(b) Name two processes by which a hot drink cools. How is the energy lost by each of these processes reduced for a hot drink supplied in a disposable cup?

(c) A thermocouple is used to measure the temperature of the steam. How would you demonstrate the principle of operation of a thermocouple?one junction (reference junction) kept cold / at constant temp

3other junction heated

3observation: e.g. emf /voltage developed // meter reading

3Describe how to establish a calibration curve for a thermocouple.one junction at constant temperature, other junction in water with (Hg) thermometer (state/imply) 3heat water (in steps of 10 oC approx) and note temperature and emf values (each time) 3plot graph of emf vs. temperature

3

2010 OL Q8

(a) What is heat? 6 or 3(heat is a form of) energy 6partial answer (3)

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Explain how heat transferred in a solid? 33atoms are touching / in contact 3(heat/energy transferred from) one to the other 3by vibration / without the atoms moving along 3mentions conduction / without the movement of matter / warmer to cooler (2 3)partial answer (3)Describe an experiment to compare the rates of heat transfer through different solids. 4 3apparatus: bath of water containing different rods which protrude at the same height //four different metals bars arranged like spokes and touch in the middle 3melt candle wax onto the outer end of each rod/metal and stick a matchstick/pin into the candle wax 3procedure: heat the water-bath // heat the metals over a Bunsen 3observation // conclusion: heat is conducted along the rods and the matchsticksfall off at different times // heat is transferred at different rates 3marks may be obtained from a diagrampartial answer (3)accept valid alternativesExplain the term U-value 6 or 3measure of heat transmission / measure of insulation 6partial answer e.g. insulation (3)How can the U-value of the walls of a house be reduced? 4 or 2any valid example e.g. (thicker) insulation, double glazed windows, etc. 4partial answer e.g. close windows (2)

(b)(i) How is the sun’s energy transferred to the solar collector? 3radiation / rays 3(ii) Why is the solar collector normally painted black? 3(black surfaces are) better absorbers (of heat/radiation) 3(iii) How is the heat transferred from the solar panel to the hot water tank? 3by the water flowing/pumped (through the collector and the heating coil) 3(iv) The heating coil for the hot water tank are placed at the bottom, explain why 4 or 2water is heated by convection / hot water rises, etc. 4partial answer (2)(v) Give an advantage and a disadvantage of a solar heating system 2 3any valid advantage e.g. reduces costs, unlimited supply, no pollution, etc. 3any valid disadvantage e.g. needs sun, requires a back-up, costly to install, etc. 3

2010 HL Q5

(d) Explain why snow is slow to melt as the day-time temperatures rises above 0 °C .latent heat (of snow/ice) / energy needed for change of state 4is (very) large 3(3 marks for relevant partial answer)

2009 OL Q12(b)What is meant by the temperature of a body? 6 or 3

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(measure of) hotness /coldness 6partial answer; e.g. heat (3)Name two scales that are used to measure temperature 2 x 3Celsius, Fahrenheit, Kelvin two correct 2×3one correct (3)Give the boiling point of water on each of these scales 3100 (°C), 212 °F, 373 K two correct 3one correct (2)The diagram shows a laboratory thermometer, what is its thermometric property? 3length / definition of thermometric property 3

Why is there a need for a standard thermometer? 4 or 2because different thermometric properties // thermometers respond differently // givedifferent results // to ensure a consistent measure // for calibration 4partial answer (2)

2009 HL Q5(c) Why is it necessary to have a standard thermometer?different thermometers have different thermometric properties 4give different readings (at the same temperature) 3

2009 Q11(b) Why is the bottom of a flat-plate collector blackened?good absorber 4of heat/energy/radiation 3 (d) The liquid in a vacuum-tube solar collector has a large specific latent heat of vaporisation.Explain why.more energy released/absorbed (per kg in the heat exchanger) 4during change of state 3(e) Name the three ways that heat could be lost from a vacuum -tube solar collector.conduction, convection, radiation 3+3+1(f) How is the sun’s energy trapped in a vacuum-tube solar collector?silvered walls prevent radiation 4evacuated walls prevent conduction and convection 3(g) Describe, in terms of heat transfer, the operation of a heat pump.energy taken from body/place (making it colder) 4to another body/place (making it hotter) 3(h) Give an advantage of a geothermal heating system over a solar heating system.geothermal system functions all the time // constant 4solar heating system works only during daytime // varies 3

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2008 OL Q7The temperature of an object is measured using a thermometer, which is based on the variation of its thermometric property 3(6 or 3)

(i) What is meant by temperature? 6 or 3

measure of hotness // measure of how hot / cold an object is 6

partial answer e.g. the heat in a body (3)

(ii) What is the unit of temperature? 6 or 3

°C / K 6

partial answer e.g. degrees (3) (iii) Give an example of a thermometric property 6 or 3 resistance, length (of column of mercury), emf, pressure of gas (at constant volume), colour, etc. 6 partial answer e.g. definition (3) The rise in temperature of an object depends on the amount of heat transferred to it and on its specific heat capacity 7 × 3

(iv) What is heat? 2 × 3

(form of) energy 2 × 3

partial answer e.g. work (3)

(v) Name three ways in which heat can be transferred 3 × 3 conduction 3 convection 3 radiation 3 (vi) Define specific heat capacity 2 × 3 energy required to change temperature 3 of 1 kg of material by 1 K (1 °C) 3 partial answer (3)

formula (2 × 3)

2008 OL Q11(a) State two uses of energy in the home 7 or 4 heating, cooking, lighting, TV etc two correct 7 one correct (4) (b) Give two ways to reduce energy needs in the home 7 or 4 insulate, double glaze, reduce usage, use low energy appliances, turn off unused lights, etc two correct 7 one correct (4) (c) List the main sources of renewable energy 7 or 4 solar, wind, wave, tidal, geothermal, biomass two correct 7 one correct (4)(d) What are the main parts of a solar heating system? 7 or 4 solar panel, hot water storage cylinder two correct 7

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one correct (4) (e) Why does a solar panel need to face south? 7 or 4 to get most sunlight // face sun // better output 7 partial answer (4) (f) What is the function of the backup heater? 7 or 4 for use at night // in poor sunlight // to heat radiators 7 partial answer e.g. for more heat (4) (g) Why are parts of the solar panel painted black? 7 or 4 black is a good absorber of heat // black is a poor reflector of heat 7partial answer e.g. black attracts heat (4) (h) What is the name given to the tendency of water to circulate as it is heated? 7 or 4 convection 7 partial answer (4)

2007 OL Q5(d) Name two methods by which heat can be transferred 7 or 4conduction, convection, radiation, valid examples any two 7any one (4)

2007 HL Q5(c) Why does the temperature of an athlete reduce when she perspires?(latent) heat / energy taken from body 4as perspiration / water evaporates // as water / liquid changes into steam / vapour /gas 3

2006 OL Q5(d) Give one example of a thermometric property. 7 or 4 resistance / emf / voltage / colour / volume / length / pressure, etc. any one 7 partial answer e.g. definition of thermometric property (4)

2006 OL Q7What is convection? Name two other ways of transferring heat. 4 × 3 movement of heat // hot air // cold air 3 by circulation/current // rises // sinks 3 partial e.g. incomplete answer / example (3) conduction 3 radiation 3 a labelled diagram may merit marks Describe an experiment to demonstrate convection in a liquid. 4 × 3 apparatus: beaker, liquid, dye, heat source any three 2×3 any one (3) procedure: add the dye to the liquid and heat 3 observation/conclusion: convection current visible 3 accept valid alternatives a labelled diagram may merit full marks convection in a gas, maximum 3×3 Why is insulation used to surround the bricks? Name a material that could be used as insulation. 4 × 3 prevent /reduce 3

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heat loss / energy loss 3 partial answer (3) any named insulator e.g. fibre glass / rockwool / cotton wool / aerogel etc. 2×3 partial answer e.g. lagging (3) Explain how the storage heater heats the air in the room. 2 × 4 convection // hot air rises // bricks heat by night 4 currents // cold air replaces it // heat released to the air by day 4 partial answer (4)

2006 HL Q12(c)(c) Define (i) power, (ii) specific heat capacity. (9) (i) work done per second / rate at which work is done 3 (ii) energy/heat required to raise the temperature 3 of 1 kg (of a substance) by 1 K / 1 o C 3In reality, the time taken to heat the water will be greater. Explain why. (4) energy will be lost to surroundings / absorbed by kettle / lost by evaporation // limescale on element 4

2005 Ol Q5(d) Name two methods by which heat can be transferred 7 or 4 conduction, convection, radiation, valid examples any two 7 any one (4)

2005 OL Q12(a)What does a thermometer measure? 6 or 3 temperature / hotness 6 heat (3) What are the two fixed points on the Celsius scale? 2 × 3

melting point ice / 0 ○ C3

boiling point water / 100 ○C 3 Explain the term thermometric property 2 × 3 (property that) changes (measurably / continually) 3 with (changing) temperature 3 partial answer (3) Name the thermometric property used in mercury thermometer 6 or 3 length / height / volume (of mercury column) 6 expansion (3) Give an example of another thermometric property 4 resistance (of a thermistor / conductor), emf /voltage (generated by a thermocouple), colour (of certain crystals), volume (of a gas at constant pressure), pressure (of a constant volume of gas) any one 4

2005 HL Q5(c) What is the thermometric property of a thermocouple? (7) emf / E / voltage / V / p.d. 7

2004 OL Q5

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(b) Explain the term thermometric property 4 + 3(physical property that) changes (measurably / continually) 4with (changing) temperature 3partial answer e.g. valid example (4)

2004 OL Q7What is meant by conduction? 2 × 3(transfer) of heat 3without the movement of matter / atoms // through metals / solids //atoms vibrate // (by vibration) from molecule to molecule 3Name two other ways of transferring heat 2 × 3convection / example 3radiation / example 3

Describe an experiment to show how different solids conduct heatat different rates 4 × 3apparatus: a number of different metal rods, 3heat source 3procedure: heat all the ends of the rods at the same time, rods same length andsame thickness, other valid detail 3observation/conclusion: e.g. wax melts on (different) rods at different times,(different) rods conduct heat at different rates 3accept valid alternativesa labelled diagram may merit marksGive two ways in which the U-value of a house can be reduced 6 + 2insulation / fibreglass in atticinsulation in cavity walldouble glazingcarpets any two 6 + 2any one (6)What energy conversion takes place in a solar panel? 2 × 3light / solar 3to heat 3Why are the pipes in the solar panel usually made from copper? 2 × 3good 3conductor / reference to metal 3partial answer (3)Why are the pipes in the solar panel usually painted black? 2 × 3good // poor 3absorber (of radiation) // reflector 3partial answer e.g. black attracts heat (3)Why does the warm water rise to the top of the solar panel? 2 × 3lower 3density 3convection / water expands (2 × 3)partial answer e.g. it is lighter, reference to water currents (3)

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2004 HL Q5(c) Explain the term thermometric property. (7)a (physical) property that changes measurably/continuously/uniformly, etc. 4with temperature 3

2004 HL Q7Define (i) specific heat capacity, (ii) specific latent heat. (12)

(i) energy required to raise (the temperature) // 3of 1 kg (of a substance) by 1 K // notation 3(ii) energy required to change the state (or e.g. ice to water) 3of 1 kg (of a substance) without a change in temperature 3( -1 for omission of ‘without a change in temperature’)

Allowing a liquid to evaporate in a closed pipe inside the freezer cools the air in the freezer.The vapour is then pumped through the pipe to the outside of the freezer, where itcondenses again. Explain how this process cools the air in the freezer. (12)evaporation requires latent heat / (this) change of state requires energy 6which is taken from inside the freezer / and this lowers the temperature 6The freezer causes the room temperature to rise. Explain why. (5)condensation / vapour to liquid, releases latent heat 5

2004 HL Q11

(h) Storage heaters have a large heat capacity. Explain why. (7)they are heated (only) at night / use cheap (night) tariff /contain material ofhigh specific heat capacity/ (must) release energy slowly(or during the day) 7

2003 OL Q5

(e) conduction, convection, radiation any two 7any one (4)

2003 HL Q12(b)

What is the difference between heat and temperature? (6)heat is a form of energy 3temperature is a measure of hotness (or coldness) 3(heat in Joules and temperature in Kelvin 3)The emf of a thermocouple can be used as a thermometric property.Explain the underlined terms. (10)a voltage / pd 4a property that changes 3measurably / continuously / regularly / uniformly, with temperature 3

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Name a thermometric property other than emf. Explain why it is necessary to have astandard thermometer. (12)length / pressure / volume / resistance / colour 3different thermometers 3different readings 3at same temperature / different thermometric properties 3

2002 OL Q5(d) increases conductivity/heat transferred/lost //decreases insulation 7reference to insulation/heat loss in context (7)reference to heat (4)

(g) (physical property that) changes (measurably/continually) 4with temperature (change) 3valid example (4)2002 OL Q12(b)Define 3 3heat/energy (required to) 3raise/change temperature 3of 1 kg by 1 C/1 K 3Why 4 h/mmore efficient/ hot water will rise/heats quicker/ water poor conductor/etc 4

2002 HL Q5(b) t T 273 7(Any reference to Kelvin and 273 /specific example e.g 273 K = 0o C 4)

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6th Year Physics: Electricity Theory

2013 OL Q5

(g) What colour is the wire that is connected to the fuse in a standard three-pin plug? 7 or 4 brown (red-brown) 7 partial answer e.g. blue, green-yellow (4)

(h) Give a common use for a capacitor. 7 or 4 store charge / conducts a.c. /(radio) tuning / filtering / smoothing / timing / store energy / flash camera / phone charger, etc. 7 partial answer e.g. radio (4)

2013 OL Q8

(a) An electric current is the flow of charge in a conductor when there is a potential difference between its ends. (i) Name the unit of current 6 or 3 amp / A 6 partial answer (3) (ii) Give an example of a conductor 3 any correct example e.g. named metal 3 (iii) Name a source of potential difference. 6 or 3 cell / battery / power supply, etc.

6 partial answer (3) (iv) What are the charge carriers in semiconductors? 8 or 6 or 4 electrons, holes two correct 8 one correct (6) partial answer e.g. refers to doping /intrinsic/extrinsic/P type/ N type, etc (4) (v) What type of conductor does the I-V graph in the diagram represent? 6 or 3 ohmic / metallic / wire 6 partial answer (3)

2013 OL Q11

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(a)What are the key components of the national grid? 7 or 4 (network of high voltage) transmission stations and (high voltage) power lines 7 partial answer e.g. cables, low voltage lines, transformers (4) (b) Why are high voltages used to transmit power over the national grid? 7 or 4 to avoid power/energy losses // cheaper 7 partial answer e.g. (4) (c) Why is the power supplied to domestic customers at lower voltages? 7 or 4 safety // more suitable for home uses 7 partial answer e.g. (4) (d) Name two renewable and two non-renewable energy sources used to generate electricity 7 or 4 renewable : wind, solar, wave, hydroelectric, biomass, geothermal etc. non-renewable partial answer e.g. incomplete answer (4) coal, oil, peat, gas, nuclear etc 7 (e) The national grid uses alternating current (a.c.) rather than direct current (d.c.). What is the difference between them? 7 or 4 a.c. changes direction // d.c. flows in one direction // direction // frequency 7 partial answer e.g. come from different (power) supplies (4) (f) Name the device used to convert high voltages to lower voltages? 7 or 4 (step down) transformer 7 partial answer e.g. voltage converter, rectifier (4)

(g) Give the principle of operation of the device named in part (f) 7 or 4electromagnetic induction // answer consistent with named device in (f) 7 partial answer e.g. refers the use of the device or the magnetic field (4)

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(h) Name the unit of electrical energy that is used in the delivery of electricity to homes and businesses. 7 or 4 kilowatt-hour / kWh 7 partial answer e.g. J (4)

2013 OL Q12(c)

(c) State Coulomb’s law of force between electric charges 2×3 force proportional to product of charges // F∝Q1Q2 3

inversely proportional to square of distance between them //∝ 1d2

3 partial answer (3) The diagram shows a positively-charged electroscope.

(i) Give a use for an electroscope. 6 or 3 detecting (measuring) charge / potential difference / capacitance 6 partial answer e.g. measures electricity (3) (ii) How can an electroscope be given a positive charge? 2×3 contact with // brought close to negative charge 3positive conductor // and earthed 3 partial answer (3) (iii) What is observed if you touch the cap of the electroscope with your finger? 4 or 2 leaves collapse 4 partial answer (2) (iv) Explain why this happens. 6 or 3 (negative) charge flows from earth // earthing 6 partial answer e.g. refers to charge (3)

2013 HL Q5(f), (g)

(f) Define the volt. potential difference (between two points) if 1 J (of work) is needed to move 1 C (from one point to the other) 4 + 3

(g) A positively charged rod is brought near to a neutral, conducting sphere that is on top of an insulating stand, as shown in the diagram. How would a student charge the sphere negatively by induction?earth the sphere (stated or implied) 4 remove earth (connection) and then remove rod 3

2013 HL Q8

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(a) The diagram shows a circuit used in a charger for a mobile phone. Name the parts labelled F, G and H. transformer / iron core (F) 3 diode (G) 3 capacitor (H) 3 Describe the function of G in this circuit. rectifier / converts a.c. to d.c. 6 Sketch graphs to show how voltage varies with time for (i) the input voltage (ii) the output voltage, VXY. axes correctly labelled on at least one graph 3 correct shape of input voltage (sine wave) 3 correct shape of output voltage (Straight horizontal line) 6 (–1 if no indication of smoothing effect of capacitor) (b) Electricity generating companies transmit electricity over large distances at high voltage. Explain why high voltage is used. (for a given power transmission) high voltage uses low current 3 minimising power (heat) loss 3

2013 HL Q12(c)

(c) Define the unit of charge, the coulomb. State Coulomb’s law. 1 C = charge that passes when 1 A flows for 1 s 6 correct statement of Coulomb’s law 3 Copy the diagram above and show on it the electric field generated by the charges. Mark on your diagram a place where the electric field strength is zero. correct curved deviation of the field lines on interaction 3 correct direction of field 3 (neutral/null) point marked halfway between charges 4

2012 OL Q5

(f) Why is a lightning conductor made of copper? 7 or 4 good conductor, doesn’t corrode, cheaper than silver, etc.

7 partial answer

(4)

(i) The photo shows an LDR. Draw the electrical circuit symbol for an LDR. 7 or 4

7partial answer

(4)

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2012 OL Q8

A plug is used to connect an electrical appliance in the home to the 230 volt mains supply. Modern plugs contain a small fuse which comes with a rating of 1A, 2A, 3A, 5A or 13A. The electrical energy supplied to the home is measured in kW h (kilowatt-hour). (i) What is the colour of the wire that should be connected to the fuse in a plug? 6 or 3 brown

6 partial answer e.g. blue, black, red, green-yellow

(3) (ii) Why is there a fuse in a plug? 6 or 3 protection // to prevent current overload // prevent fire, etc.

6 partial answer

(3) (iii) Explain how a fuse works. 6 + 3 when the current exceeds a certain value the wire breaks / fuse burns out / circuit breaks two lines correct 6 + 3 one line correct

(6) partial answer

(3) (vi) Name a device found in modern domestic circuits that has the same function as a fuse. 6 or 3 (miniature) circuit breakers / MCBs // trip switches // residual current devices / RCDs // trip switch / RCB / ELCB, etc.

6 partial answer

(3)

2012 OL Q12(d)

Part (d) A capacitor is connected to a switch, a battery and a bulb as shown in the diagram. When the switch is changed from position A to position B, the bulb lights briefly.

(i) What happens to the capacitor when the switch is in position A? 6 or 3 it charges / short-lived current flows / stores energy

6 partial answer e.g. current flows

(3)

(ii) Why does the bulb light when the switch is in position B? 6 or 3 capacitor discharges / current flows // (switch) closes the circuit

6 partial answer

(3)

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(iii) Why does the bulb light only briefly? 6 or 3 capacitor discharges quickly / p.d. fades / current transient / capacitor only holds small charge / capacitor only stores a small amount of energy

6 partial answer

(3)

(v) Give a use for a capacitor. 4 or 2 store charge / (radio) tuning / filtering / smoothing / timing / coupling / store energy / flash camera / phone charger, etc. one correct

4

2012 HL Q9

Define resistance.voltage ÷ current / ratio of voltage to current / V ÷ I plus correct notation

3

(i) Two resistors of resistance R1 and R2 are connected in series. Derive an expression for the effective resistance of the two resistors in terms of R1 and R2.

(ii) Two 4Ω resistors are connected in parallel. Draw a circuit diagram to show how another 4Ω resistor can be arranged with these two resistors to give an effective resistance of 6Ω .

(iii) A fuse is a resistor used as a safety device in a circuit. How does a fuse operate?fuse in live part of circuit 3

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gets hot if current exceeds a certain (rated) value (state/imply) 3

melts/breaks 3

circuit is broken 2

A Wheatstone bridge circuit is used to measure the resistance of an unknown resistor R.The bridge ABCD is balanced when X = 2.2 kΩ, Y = 1.0 kΩ and Z = 440 Ω.

(iv) What test would you use to determine that the bridge is balanced?connect galvanometer (G) / millivoltmeter (mV) across points AC

3no deflection in G (when balanced)

3

(vi) When the unknown resistor R is covered by a piece of black paper, the bridge goes out of balance.What type of resistor is it?light dependent resistor / l.d.r. / photoresistor / CdS cell

3Give a use for this type of resistor.used in light meters / (to control) street lights / security alarms / (control) traffic lights /used in re-charging circuits, etc.any one valid answer

3

2012 HL Q11(g)

(g) Small scale wind turbines are sometimes used to charge batteries. The a.c. output voltage has to be converted to a d.c. voltage. How is this achieved?diode / rectifier 7

2011 OL Q5

(g) What is the colour of the earth cable in a standard 3-pin plug? 7 or 4

yellow & green 7partial answer e.g. yellow, green, correct colour of other cable (4)

(h) How does a miniature circuit breaker (MCB) improve safety in a domestic circuit? 7 or 4

prevent too high current flowing // turns off current 7partial answer e.g. incomplete answer (4)

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(i) Give a use for an electroscope 7 or 4

test for charge, identify charge, measure potential, etcone correct 7partial answer (4)

2011 OL Q12(c)(c) What is an electric current, and give its unit of measurement? 3 x 3flow / movement 3of charge / electrons 3amp /A 3

State the three effects of an electric current. 4 or 2magnetic, heating/lighting, chemical two correct

4one correct (2)

How would you demonstrate one of these effects? 3 x 3apparatus; e.g. filament bulb, battery, leads 3procedure; e.g. connect up circuit and pass current through the bulb 3observation / conclusion; e.g. the bulb lights / gets hot 3valid alternativespartial answer (3)

2011 HL Q5(f)

(f) A residual current device (RCD) as shown is rated 30 mA. Explain the significance of this rating.RCD / device trips 4if more than 30 mA flows to earth / the current difference between L and N is greater than 30 mA 3

2011 HL Q9

(a) State Coulomb’s law. (6)

(force) inversely proportional to square of distance // correct notation 3

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(b) Draw a labelled diagram of an electroscope.(metal ) cap, labelled leaves, chassis/frame (–1 if no label)

3Why should the frame of an electroscope be earthed?p.d. between leaves and chassis/frame (determines degree of deflection of leaves) / for safety 3( reference to ‘zero volt’ … 3 marks)Describe how to charge an electroscope by induction.hold (say) + charged rod near cap of (uncharged) electroscope

3earth cap (touch with finger)

3remove finger and then remove + rod

3(c) How does a full-body metal-foil suit protect an operator when working on high voltage power lines?(suit) blocks out external electrical fields / no field lines inside (hollow conductor)

5Describe an experiment to investigate the principle by which the operator is protected.apparatus 3procedure 3observation 3conclusion 3

2011 HL Q11

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(f) A light sensor attached to a datalogger indicates that the light emitted from a CFL used in the home is not continuous, but flickers at a frequency that is not detected by the eye. What is the cause of the flickering in the light?(house) power supply is alternating / a.c. (state/imply) 7

(g) Draw a circuit diagram of a diode in forward bias.

7

(correct diode symbol / structure … 3 marks)(4 marks only if no suitable device, e.g. R or a bulb, shown in series with diode and p.s.u.)

(h) How can LEDs be used to produce white light?mixture of leds (4)red, green and blue leds 7(‘coat LEDs with fluorescent/phosphorescent material’ …. 7 marks)

2011 Hl Q12(c)

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(c) List the factors that affect the heat produced in a current-carrying conductor.resistance, current (squared), time, (any valid answer) 3+2+2

2010 OL Q5

(h) Give a common use of capacitors? 7 or 4store charge // tune radio // flash guns // smoothing // filtering // etc. 7partial answer e.g. used in radios/cars (4)

(i) In relation to semiconductors, what is meant by the term doping? 7 or 4adding impurity/atoms and a relevant detail e.g. to change conductivity 7partial answer e.g. adding impurities, adding a substance (4)

2010 OL Q9

(a) State Coulomb’s law of force between electric charges. 3 3force proportional / F 3product of charges / Q1Q2 3inversely proportional to the square of the distance between them / 1/d2 3(i) How would you detect the presence of an electric field? 3 3using an electroscope // electric field sensor // electric field meter 3 3

using a meter // charged object/fluorescent bulb (2 3)partial answer e.g. mention of charge, detects magnetic field (3)(ii) What is the unit of electric charge? 4 or 2coulomb / C 4partial answer e.g. other electrical unit (3)

(iii) How does the lightning conductor prevent damage to the building? 6 or 3provides (safe) path for flow of current if struck // it earths the building //allows easy path for discharge //other suitable explanation 6partial answer (3)(iv) Suggest a suitable material for a lightning conductor 4 or 2metal / named metal e.g. copper / aluminium 4partial answer (2)(b) State Ohm’s law 6 or 3V I // V = I R (at a constant temperature) 6V / I / R / / at a constant temperature (3)

2010 OL Q12(c)

The diagram shows a plug which contains a fuse, an MCB and an RCD(i) Explain how a fuse works 2 3

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wire melts, with too high a current, breaking circuit two correct 2 3one correct (3)(ii) How does the fuse improve safety? 4 or 2prevents too high a current flowing / reduce fire risk 4partial answer (2)(iii) What is an MCB? 3miniature circuit breaker / trip switch / safety device 3(iv) What is the function of an RCD? 6 or 3to protect against electrocution /shut off current in event of a fault /safety switch 6partial answer e.g. safety, residual-current device (3)(v) Why should an appliance be earthed? 6 or 3provide path for current in event of a fault // to protect against electrocution 6partial answer e.g. safety (3)(vi) Give one other precaution that should be taken to improve safety whenusing electricity in the home 3do not use appliances near water / do not overload sockets, etc. 3

2010 HL Q5(f) Which of the following devices is adjusted when tuning into a radio station?transformer diode capacitor rheostat

(tuning) capacitor 7

2010 HL Q8

A hair dryer with a plastic casing uses a coiled wire as a heat source. When an electric currentflows through the coiled wire, the air around it heats up and a motorised fan blows the hot air out.What is an electric current?a flow of charge / e– 6Heating is one effect of an electric current. Give two other effects of an electric current.magnetic 3chemical 3The diagram shows a basic electrical circuit for a hair dryer.(i) Describe what happens:(a) when switch A is closed and the rheostat is adjustedfan operates and its speed (of rotation) changes 3(b) when switch A and switch B are closed.charge/current flows through coil // coil gets hot 3fan blows hot air 3

(iv) Explain why the current through the coil would decrease if the fan developed a fault andstopped working.coil gets hot 4its R increases 4(any correct statement explaining why Rcct or Rcoil has increased…. 2 × 4)

2010 HL Q12(d)

(d)Define electric field strength and give its unit of measurement.

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force // E = F / q 3per unit charge // correct notation 3N C–1 / V m–1 3Copy the diagram into your answerbook and show on it the direction of the electric fieldat point P.

3Under what circumstances will point discharge occur?large electric field strength /potential at a point / high charge density at a point 4

2009 Q5(g) Name the instrument shown in the diagram? 7 or 4(gold leaf) electroscope 7partial answer; e.g. gold leaf (4)

2009 OL Q8Plugs are used to connect electrical appliances in the home to the 230 volt ESB supply.Modern plugs contain a small fuse which comes with a rating of 1A, 2A, 3A, 5A or 13A.The electrical energy supplied by ESB to the home is measured and charged for in kWh(kilowatt-hour).(i) What is the colour of the wire that should be connected to the fuse in a plug? 6 or 3brown 6red / blue / green-yellow (3)(ii) What is the function of a fuse? 6 or 3prevent too high a current flowing / safety device / prevent overheating / prevent fire 6partial answer (3)(iii) Explain how a fuse works 6 + 3(thin wire) heats up / breaks /meltsstops flow of current /breaks circuit / if current too hightwo correct 6+3one correct (6)partial answer (3)(iv) Name another device with the same function as a fuse 4 or 2circuit breaker /trip switch/ RCD/MCB 4partial answer; e.g. switch, earthing, bonding, other safety device (2)(vi) Why would it be dangerous to use a fuse with too high a rating? 6 or 3would allow too large a current to flow / device could overheat / danger of fire 6partial answer (3)

2009 OL Q12(c)A p-n junction (diode) is formed by doping adjacent layers of a semiconductor,and a depletion layer is formed at the junction 6 + 3doping: addition of impurity (to semiconductor) / changes its conductivitysemiconductor: material with (resistivity) between that of conductors and insulators

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two correct 6+3one correct (6)partial answer; e.g. p-type / n-type (3)How does the depletion layer form? 6 or 3holes and electrons recombine 6partial answer; e.g. reference to holes and electrons (3)The diagram shows two diodes connected to two bulbs A and B, a 6 V d.c.supply and a switchWhat is observed when the switch is closed? 6 or 3diode A lights // B does not light 6partial answer (3)Explain why this happens 7 or 4A is forward biased // B is reverse biased // depletion layer removed in A / depletion layer increases in B 7partial answer (4)

2009 HL Q5

(f) Define electric field strength.E = F/q // force 4correct notation // per unit charge 3(g) When will an RCD (residual current device) disconnect a circuit?(when magnitude of the) current flowing in differs // leakage of current 4from that flowing out // to earth (ground) 3

2009 HL Q9

Describe an experiment to demonstrate that a capacitor stores energy.apparatus: capacitor, p.s.u., (bulb) 3method:charge capacitor (C) // connect capacitor across p.s.u. 3discharge C (through bulb) 4result:(bulb) flashes/lights 4

2009 Q12(b)A semiconductor diode is formed when small quantities of phosphorus and boron areadded to adjacent layers of a crystal of silicon to increase its conduction.Explain how the presence of phosphorus and boron makes the silicon a better conductor.more electrons available (as charge carriers when phosphorus is added ) 3more (+) holes (as charge carriers when boron is added ) 3

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What happens at the boundary of the two adjacent layers?electron and holes cross (junction) // electrons move/migrate 3no free charge carriers /depletion layer formed // from n-type to p-type (region) 3junction voltage (created) // junction voltage / depletion layer formed 3Describe what happens at the boundary when the semiconductor diode is(i) forward biased, (ii) reverse biased.(i) width of depletion reduced / (diode) conducts / conduction(ii) width of depletion layer increased / no conduction (any order, once correct) 6 + 3Give a use of a semiconductor diode.rectifier (any valid use) 4

2008 OL Q5(f) Give one effect of static electricity? 7 or 4 lightning, static discharge, receive shock after walking across carpets, attracts objects, causesmaterials to repel, causes hair to stand on end, can damage electronics, causes sparks, etc. one correct 7 partial answer e.g. photocopying (4) (g) Give two uses for the instrument shown. 7 or 4 voltmeter, ammeter, ohmmeter, temperature, frequency, other known use of multimeter two correct 7one correct (4) (h) What is the colour of the live wire in an electric cable? 7 or 4 brown 7 black, red, blue (4)

2008 OL Q9An electric current flows in a conductor when there is a potential difference between its ends.

(i) What is an electric current? 2 × 3 flow of / movement 3 charge / electrons / electricity 3 partial answer e.g. refers to amps (3) (ii) Give two effects of electric current. 2 × 3 heating / lighting, magnetic, chemical two correct 2×3 one correct (3)

(iii) Name a source of potential difference. 4 or 2 battery / generator / thermocouple etc 4

partial answer (2)

Describe an experiment to investigate if a substance is a conductor or an insulator . 2×2 + 2×3

apparatus: circuit to show power source, ammeter/ bulb, leads, contacts two correct 2×2 procedure: connect the circuit and place item between contacts 3observation/conclusion: bulb lights / item conductor // bulb does not light / item is an insulator 3

The two headlights of a truck are connected in parallel to a 24 V supply.

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(i) Draw a circuit diagram to show how the headlights are connected to the supply. 6 or 3 circuit diagram showing battery, two bulbs, connected in parallel 6 partial answer. (3) (ii) What is the advantage of connecting them in parallel? 6 or 3 brighter / more current to each / if one goes the other still works, etc 6 partial answer (3) (iii) Why should a fuse be included in such a circuit? 6 or 3 safety / prevent overheating or fire / prevent too high a current flowing 6 partial answer (3)

2008 HL Q5(g) What are the charge carriers when an electric current

(i) passes through a semiconductor; (ii) passes through an electrolyte?

(i) electrons and (positive) holes 4 (ii) ions 3

(h) Give two ways of deflecting a beam of electrons. (by means of) an electric field and a magnetic field (any order) 4+3

2008 HL Q7

An electric toaster heats bread by convection and radiation. What is the difference between convection and radiation as a means of heat transfer? convection requires a medium, radiation does not (or correct reference to vacuum) / movement of medium in convection, no movement of medium with radiation, etc. any correct comparison

4 + 4 The toaster has exposed metal parts. How is the risk of electrocution minimised? (metal parts are) earthed / reference to RCD / reference to (double) insulation / etc. 9

(award 6 marks for any relevant safety feature) When the toaster is on, the coil emits red light. Explain, in terms of movement of electrons, why light is emitted when a metal is heated.

electrons excited/gain energy 3 jump to higher energy state 3 return to lower state 3

emit energy / emr /i.r / light / photon 3 [(4 × 3) marks awarded for appropriate diagram]2008 HL Q12(d)(d) Define capacitance. (ratio of )charge // c=Q

v 3 to/over potential / per unit voltage // correct notation 3

( –1 per incorrect/omitted item)

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Describe how an electroscope can be charged by induction. charged object adjacent to electroscope 4

earth electroscope (briefly) 3 remove charged object 3 (award full credit for a correct sequence of diagrams: award a maximum of 4 marks if ‘conduction’ is used) How would you demonstrate that the capacitance of a parallel plate capacitor depends on the distance between its plates? arrangement: connect digital multimeter with capacitance setting (state/imply) to plates 3 method: switch on meter (state/imply) 3 (slowly )separate plates 3 observation: capacitance (reading) is lowered 3

Alternative method: arrangement: connect electroscope correctly to parallel plate capacitor (3) method: (earth one plate and) place a charge on the other (using a h.t. power supply) (3) (slowly) separate plates (3) observation: leaves diverge indicating (voltage increasing) capacitance is lowered (3)

2007 OL Q5(g) Name two safety devices that are used in domestic electric circuits 7 or 4fuse, (trip) switch, miniature circuit breaker / MCB, residual currentdevice / RCD, earthing, bonding, etc. any two 7any one (4)(h) Name the electrical component represented in the diagram 7 or 4LDR / light dependant resistor 7partial answer e.g. mention of resistor / thermistor / light (4)

2007 OL Q9(a)State Coulomb’s law of force between charges 3 × 3force proportional / F ∝ 3product of charges / Q1Q2 3

inversely proportional to the distance between the charges squared / 3

(i) Describe how an electroscope is given a positive charge 3 × 3charge a rod (negatively) //charge a rod (positively) 3bring the (charged) rod close to the cap and earth // touch the cap with (charged) rod 3remove the earth before removing the rod // metal / conductor (rod) 3accept valid alternatives e.g. Van De Graafflabelled diagrams may merit full marks(ii) What is observed when the cap of an electroscope is earthed?

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Why does this happen? 6 + 3What? leaves drop / fall 6Why? (negative) charges move from the earth (to the cap) 3(iii) How is the cap of the electroscope earthed? 6 or 3touch (with finger) 6partial answer (3)

(b) A capacitor is connected to a switch, a battery and a bulb as shown in the diagram.When the switch is moved from position A to position B, the bulb lights briefly(i) What happens to the capacitor when the switch is in position A? 6it charges / stores charge / stores energy 6partial answer e.g. gets hot (3)(ii) Why does the bulb light when the switch is in position B? 6 or 3capacitor discharges // current flows 6partial answer e.g. closed circuit (3) (iv) Give a use for a capacitor 5 or 3store charge, (radio) tuning, filtering, smoothing, timing, coupling,store energy, flash camera, phone charger, etc. any one 5partial answer e.g. storing electric current (3)

2007 OL Q12(c)State Ohm’s law 6 or 3V ∝ I // V = I R 6V / I / R / ∝ / at a constant temperature (3)Name an instrument used to measure the potential difference 4 or 2voltmeter / multimeter 4partial answer e.g. ammeter (2)

2007 HL Q8Define electric field strength and give its unit of measurement.force // (E =)F / q 3per unit charge // correct notation 3N C-1 or V m-1 3Describe how an electric field pattern may be demonstrated in the laboratory.apparatus oil, metal plates, container, semolina, H.T. ( -1 for each omission) 3arrangement correct arrangement 3procedure switch on power (state or imply) 3observation semolina particles line up (to show field pattern) 3All the charge resides on the surface of a Van de Graff generator’s dome. Explain why.like charges repel 3charges are a maximum distance apart (on outside/surface of dome) 3Describe an experiment to demonstrate that total charge resides on the outside of a conductor.apparatus: metal can, gold leaf electroscope, proof plane ( -1 for each omission) 3procedure: charge metal can and use proof plane to test inside and outside 3observation: leaves on g.l.e. deflect for outside sample only 3conclusion: charge resides on outside only 3(experiment could also be performed using a butterfly net)Give an application of this effect.electrostatic shielding / co-axial cable / TV (signal) cable

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/ to protect persons or equipment, enclose them in hollow conductors/Faraday cages (there is no electric field inside a closed conductor), etc.any relevant application 2

2007 HL Q9Define (i) resistancevoltage // V / I or P / I2 3divided by current /per unit current // correct notation 3(ii) resistivity.the resistance // RA/L 3of a cube of material of side 1 m // correct notation 3Sketch a graph to show the relationship between the temperature and the resistance of the nichrome wire as its temperature is increased.axes labelled R and T (or θ ) 3correct linear graph with intercept showing R greater than zero (-1 if line passes through origin) 3

What happens to the resistance of the wire:(i) as its temperature falls below 0oC?R decreases 3(ii) as its length is increased?R increases 4(iii) if its diameter is increased?R decreases 4Name another device, apart from a metre bridge, that can be used to measure resistance.ohmmeter / wheatstone bridge / /multimeter / DMM / ammeter + voltmeter any one 6Give one advantage and one disadvantage of using this device instead of a metre bridge.ohmmeter: compact, portable, faster method, etc. less accurate, fragile, difficult to calibrate/check,wheatstone bridge: compact, portable, more accurate etc. ‘black box’ difficult to comprehend, expensive,ammeter +voltmeter: easy to use, easy to understand, etc. range selection difficult, fragile, less accurateone advantage + one disadvantage of the chosen device 2 + 1

2007 HL Q11(f) Why is silicon a semiconductor?it has a resistivity / resistance / conductivity 4between that of a conductor and an insulator 3(“it’s neither a good conductor nor a good insulator”….. 7 marks)(R decreases with (increasing) T 7 marks)

2006 OL Q5(g) Name the electrical component represented in the diagram. 7 or 4 variable resistor / rheostat / potentiometer 7 partial answer e.g. resistor / thermistor or function (4)(h) State Ohm’s law. 7 or 4 V ∝ I / V = I R 7 V / I / R / ∝ (4) (i) Give one use of a capacitor. 7 or 4 store charge / (radio) tuning / filtering / smoothing / timing / coupling /

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store energy / flash camera / phone charger, etc. 7 partial answer e.g. storing electric current (4)

2006 OL Q11(a) Give one use for electricity in the home. 7 heating / cooking / lighting /named electrical appliance etc. 7 (b) What is the function of the ESB meter? 7 record units used / enable customer costing 7 (c) What will happen when a current of 20 A flows through a fuse marked 13 A? 7 fuse blows / current stops / switch trips 7 (d) Give one safety precaution that should be taken when wiring a plug. 7 screw connections are fully tightened / leave extra slack on the earth wire / fit the correct size fuse / ensure to match the colour codes 7 (e) What is the colour of the earth wire in an electric cable? 7 green and yellow 7 (f) Name a common material used to conduct electricity in electric cables. 7 copper / aluminium 7 (g) Why is the coating on electric cables made from plastic? 7 insulator / safety 7 (h) Why are some appliances not earthed? 7

they are double insulated / they have insulated housing 7

2006 OL Q12(d)A semiconductor material can be doped to form a p-n junction (semiconductor diode). Explain the underlined terms. 2(2 × 3) a semiconductor has a resistivity / conductivity 3 between a conductor and an insulator / changes (rapidly) with temperature 3 partial answer e.g. has a big resistance / not a good conductor (3) (p-n junction is the) region connecting p-type (semiconductor) 3 to an n-type semiconductor 3 partial answer e.g. mention of junction voltage / depletion layer / holes / free electrons/ intrinsic/ extrinsic (3) a diagram may merit full marks Name a material used as a semiconductor. 6 or 3 Silicon / Si, germanium / Ge, Aluminium nitride, Boron nitride, etc. any one 6 partial answer e.g. any other element with four electrons in its outer shell (3)

The circuit diagram shows 2 semiconductor diodes and 2 bulbs, labelled A and B, connected to a 6 V d.c. supply. What is observed when the switch is closed? Explain why? 4 + 2 × 3 (bulb) B lights // (bulb) A does not light 4 diode near B // diode near A 3 conducts / forward biased // does not conduct / reverse biased 3

2006 HL Q5(f) An RCD is rated 30 mA. Explain the significance of this current. (7) RCD trips /switches off / breaks circuit (at 30 mA or greater) 7

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(g) Why is Coulomb’s law an example of the inverse square law? (7) F α // force inversely proportional to 4 1/d2 // distance squared 3 [Formula or expression …. 3 marks. Specific example, e.g. d x 2 F/4 … 7 marks](h) Sketch a graph to show the variation of current with potential difference for a semiconductor diode in forward bias. (7) I V labelled graph with non-linear curve 4 correct shape 3

2006 Hl Q9What is an electric current? Define the ampere, the SI unit of current. (12) flow of charge / electrons (and + holes) 3 two (infinitely) long parallel wires (of negligible cross-sectional area) 3 1 m apart in vacuum 3 experience a force of 2 x 10-7 N per metre (length) 3 Describe an experiment to demonstrate the principle on which the definition of the ampere is based. (15) power supply , (two) aluminium(foil) strip(s)/ conducting strip(s) 3 correct arrangement (maybe shown in diagram) 3 (indicate means of keeping) strips parallel 3 switch on current 3 strips move / repel 3

Sketch a graph to show the relationship between current and time for (i) alternating current; (ii) direct current. (9)

(i) axes labelled (I and t) 3 sinusoidal curve (at least one full wave) 3 [ -1 if + and – current not shown] (ii) (axes labelled if not already done in a.c. graph showing) correct curve 3 Explain why the resistance of the bulb is different when it is not connected to the mains. (5) cold filament /coil // hot filament /coil 3 has lower resistance // has higher resistance 2

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‘resistance of coil depends on temperature ‘ / different coil temperatures result in different resistance (values) / heating changes resistance of coil (3)

2006 HL Q12(b)(b) List the factors that affect the capacitance of a parallel plate capacitor. (6) (common) area (of plates), distance (apart), permittivity (of dielectric) / dielectric / medium (between plates) 3 x 2 What is the net charge on the capacitor? Give a use for a capacitor. (7) (net charge) = 0 4 blocks d.c. /smoothing /tuning circuits / timing circuits / flash guns (for cameras) 3 ( any valid answer)

2005 OL Q5(g) Name the electrical component used in the diagram 7 or 4 diode, accept LED, p-n (junction) 7 partial answer e.g. semiconductor, transistor (4) (h) Name two safety devices that are used in domestic electric circuits 7 or 4 fuse, trip switch / miniature circuit breaker / MCB, residual current device / RCD, earthing, bonding, etc. any two 7any one (4)

2005 OL Q8State Ohm’s Law. 3× 3 voltage / pd / V 3 proportional to /∝ / = R 3 current / I 3 partial answer e.g. when the temperature is kept constant, (3) Which conductor obeys Ohm’s law? Explain your answer 6 + 2 × 3 graph (a) / metal 6 straight line 3 through origin // shows proportionality 3 As the thermistor is heated, what happens to 2x(6 or 3) (iv) the resistance of the circuit?

decreases / increases 6 partial answer e.g. varies, indication of change in resistance (3)

(v) the potential difference across the 100 Ω resistor? answer consistent with (iv) 6 partial answer e.g. varies, indication of change in the voltage (3)

Give a use for a thermistor 5 thermometer / heat sensor / temperature control / circuit control 5 partial answer e.g. change the resistance/voltage in circuits (3)

2005 OL Q12(c)Name the GLE parts labelled A and B 2 × 3 A = insulation, any named insulator 3 B = metal/glass/plastic case 3 Give one use of an electroscope 2 × 3

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measure/ detect // identify 3 voltage / potential / charge // sign of charge 3 Explain why the gold leaf diverges when a positively charged rod is brought close to the metal cap 3 × 3 electrons attracted up / positive charge repelled down 3 leaves more positive 3 leaves repel 3 labelled diagram may merit marks The positively charged rod is held close to the electroscope and the metal cap is then earthed. Explain why the gold leaf collapses 4 + 3 charge / any named charge carrier 4 flows to ground 3

2005 HL Q5(g) A pear-shaped conductor is placed on an insulated stand is shown. Copy the diagram and show how the charge is distributed over the conductor when it is positively charged. (7) concentration of charge at pointed end 4 charge indicated throughout the conductor 3 (h) Explain why high voltages are used in the transmission of electrical energy. (7) high voltages smaller currents (required for equivalent power transmission) 4 less power / heat / energy losses 3

2005 HL Q9Define (i) potential difference. (6) work done // V = W / Q 3 moving unit charge between two points // notation 3 (ii) resistance. (6) R = V/I // voltage per 3 notation // unit current 3

Two resistors, of resistance R1 and R2 respectively, are connected in parallel. Derive an expression for the effective resistance of the two resistors in terms of R1 and R2 . (12) IT = I1 + I2 3 (apply Ohm’s law ) V = IR 3 V/RT = V/R1 + V/R2 3 1/RT = 1/R1 + 1/R2

3 As the temperature of the room increases, explain why: (iii) the resistance of the thermistor decreases (7) more energy added to the thermistor / temperature of Th3 increases 3 (more) electrons produced / released 2 (resistance is reduced because) more electrons /charge carriers are available for conduction 2 (iv) the potential at A increases. (7)

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resistance of thermistor (and 750 Ω combination) decreases 3 potential difference across thermistor and 750 Ω combination decreases 2 potential at A increases 2

2005 HL Q10Define electric field strength. (6) E = F/Q // force per 3 notation // unit charge 3

State Coulomb’s law of force between electric charges. (6) force proportional to product of charges // F = Q1Q2/4πεr2 // F ∝ Q1Q2/r2

3 inversely proportional to square of distance // notation // notation 3 Why is Coulomb’s law an example of an inverse square law? (6) (because) F is proportional to 1/d2 / as distance is doubled force decreases by a factor of 4 6

Give two differences between the gravitational force and the electrostatic force between two electrons. (6) gravitational force is much smaller (than the electrostatic force) 3 gravitational force is attractive, electrostatic force is repulsive 3

Describe an experiment to show an electric field pattern. (12) high voltage /H.T / E.H.T. and two metal plates /electrodes 3 semolina and oil in container 3 connect a (high) voltage to the plates (in container) 3 semolina lines up in the field 3

2004 OL Q5(f) Name the electrical component represented in the diagram 7 or 4capacitor / condenser 7partial answer e.g. parallel plate, stores charge, battery (4)(g) Name two safety devices that are used in domestic electric circuits 7 or 4fuse, (trip) switch / miniature circuit breaker / MCB, residual currentdevice / RCD, earthing, etc. any two 7any one (4)2004 OL Q9What is an electric current? 6 + 3flow of / movementcharge / electrons / electricity two lines 6+3one line (6)partial answer e.g. unit (3)Name two other effects of an electric current 6 + 3magnetic / deflects compasschemical two lines 6 + 3one line (6)partial answer e.g. light / sound (3)Describe an experiment to show the heating effect of an electric current 4 × 3apparatus: source e.g. power supply 3

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conductor e.g. bulb, wire 3procedure: set up the circuit / allow current to flow 3observation/conclusion: wire gets hot 3accept valid alternativesa labelled diagram may merit marksState two factors on which the heating effect of an electric current depends 2 × 3size of current, (size of) voltage, resistance / length of coil, amount of time any two 2 × 3What is the kilowatt-hour? 2 × 3energy 3used by a 1 kW (appliance/device) in 1 hour 3unit used by the ESB (2 × 3)partial answer e.g. reference to joule (3)

2004 HL Q5What is electromagnetic induction? 2 × 3emf / voltage / potential difference / current is induced 3(due to)changing (magnetic) flux / field // moving magnet 3

Name another device that is based on electromagnetic induction 3dynamo, generator, induction motor, induction cooker, etc. any one 3

Name the parts of the transformer labelled A, B and C in the diagram 6 + 3A = primary / input (coil)B = secondary / output (coil)C = (iron) core / former any two 6 + 3any one (6)partial answer e.g. coil in A or B, reference to step-up (transformer) (3)

What is the voltage across B? 10 or 6 or 3690 (V) / three times bigger 10correct substitution into both sides of the equation / ≈ 77 / three times smaller (6)partial answer e.g. correct substitution into one side of the equation (3)

2004 HL Q8

Describe an experiment to demonstrate that a capacitor can store energy. (12)apparatus: capacitor, cell, bulb / wire (for shorting C) 3connect cell to capacitor / charge capacitor 3

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connect bulb across capacitor // short terminals of capacitor 3bulb lights // spark 3Describe what happens in the circuit when the 6 V d.c. supply is replaced with a 6 V a.c.supply. (5)charge / current flows // C charges 3all of the time / forwards and backwards // discharges 2(“C conducts all of the time”… 5. “C conducts” … (5-1) =4 )

2004 HL Q11(a) Name and give the colour of the wire that should be connected to the fuse in a standardthree-pin plug. (7)live / phase 4brown / red 3(b) Explain why replacing a fuse with a piece of aluminium foil is dangerous. (7)does not melt /break // can carry a very large current 4if too large a current flows // fire / (fatal) shock 3 (d) Some electrical appliances are supplied with two pin plugs. Why is an earth wire notrequired in these devices? (7)(all) external parts 4electrical insulators / non-conducting / named insulator 3‘appliance is doubly insulated’ (7); ‘no danger/risk of shock’ (4)(e) Sketch a voltage-time graph of the 230 V supply. (7)varying voltage 4sinusoidal waveform 3( -1 if at least one full cycle is not shown: -1 if no negative voltage shown.)

(f) Explain how a Residual Current Device (RCD) operates. (7)measures/detects current in live and neutral 4trips/shuts off if there is a difference(between them) 3

(g) Give one advantage of a Residual Current Device (RCD) over a Miniature CircuitBreaker (MCB). (7)RCD responds v. quickly / RCD responds to tiny currents 7RCD prevents electrocution / is safer ... (4)

2004 Q12(d)A p-n junction is formed by taking a single crystal of silicon and doping separate butadjacent layers of it. A depletion layer is formed at the junction. (15)

(i) What is doping?adding a (controlled) quantity of an impurity (to the crystal) / Al / P / etc. 3to increase conduction / to form p- / n-type material 3(ii) Explain how a depletion layer is formed at the junction.electrons from n-type and/or holes from p-type 3

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cross junction 3(narrow) charged region acts as a ‘barrier’ or depletion layer 3(correctly labelled diagram 3 × 3)The graph shows the variation of current I with potential V for a p-n junction in forwardbias. (13)Explain, using the graph, how the current varies with the potential difference.very little current flows between 0 V and 0.6 V 3> 0.6 V a large current flows 3Why does the p-n junction become a good conductor as the p.d exceeds 0.6 V?the depletion layer / barrier potential / junction voltage // width of depletion layer 4is overcome // reduced 3[“(effective) resistance lowered (4) and this results in a larger current flow” 7]

2003 OL Q8What is an electric current? 2 × 3flow of / movement 3charge / electrons / electricity 3unit (3)Give the standard colour of the insulation on the wires 3 × 3L (live) is brown // red 3N (neutral) is blue // black 3E (earth) is green-yellow / green / yellow 3two correct colours which are mismatched (3)What is the purpose of the wire connected to the terminal E on the plug? 6 or 3(earth wire) protects from electrocution / shock // (ensures) potential at zero //draws / conducts (leaking) current to earth / ground (safely) 6partial answer /earth / protection / fuse blows / safety (3)Explain why a fuse is used in a plug 2 × 3prevents // protects people or equipment from // safety (from) 3large current 3partial answer (3)

This current will only flow for a very short time. Explain why 6 or 3current / 8.7 (A) larger than fuse rating // current too big // fuse blows 6partial answer (3)How does bonding improve safety in the home? 6 + 3earth / potential at zero / low potential // prevents electrocution 6metal pipes connected / taps connected 3partial answer / safe (3)Name a device that is often used in domestic electric circuits instead of fuses 5 h/m(miniature) circuit breakers / MCBs // trip switches //residual current devices / RCDs 5

2003 OL Q11(a) (resistivity) between that of a conductor and insulator 7neither a good conductor nor a good insulator (7)partial answer / valid example / reference to p-type or n-type material (4)(b) silicon / germanium / selenium etc. 7(c) (positive) holes and electrons 7one correct (4)

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partial answer e.g. positive and negative (4)(d) adding (suitable) impurities (to improve conductivity) 7partial answer e.g. reference to extrinsic (4)(e) p-type material contains more holes (than n-type material) 7n-type material contains more (free) electrons (than p-type material) (7)partial answer / valid example (4)(f) (the junction) between the p-type and the n-type material (in contact) 7partial answer (4)labelled diagram may merit full marks(g) a device that contains a p-n junction // allows current to flow in onedirection only 7partial answer e.g. contains a depletion layer // named example e.g. LED (4)(h) radio, television, computer, battery charger, mobile phone charger etc. any one 7

2003 OL Q12(c)What is the unit of electric charge? 6 or 3coulomb / C 6amp (3)Describe, with a labelled diagram, how to charge a conductor by induction 4 × 3apparatus e.g. conductor (mounted on insulated stand) and a chargedobject / rod 3procedure hold / bring the charged rod near the conductor 3earth the conductor (while the charged rod is near) 3remove the earth then the charged rod 3a labelled diagram may merit markscharge by friction, maximum 2 × 3NOTE: no labels, deduct 2Give two examples where build-up of electric charge can lead to explosions 2 × 3dust e.g. flour mill explosions, inflammable vapours e.g. fuelling aircraft,lightning any two 2 × 3How can the build-up of electric charge on an object be reduced? 4 h/mearthing / grounding 4

2003 HL Q5(g) What is the purpose of a miniature circuit breaker (MCB) in an electric circuit?behaves as a fuse / to break the circuit // safety device 4when too large a current flows // prevents too large a current 3

2003 HL Q8Define the unit of current, i.e. the ampere. (9)two (infinitely) long parallel wires (of negligible cross section) 31 metre apart in vacuum 3(force of) 2x10-7 N m-1 3Describe an experiment to demonstrate the principle on which the definition of theampere is based. (15)(aluminium) foil / wires 3parallel strips 3a circuit 3when current is switched on 3

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foil moves 3Various materials conduct electricity. Draw a graph to show the relationship between current and voltage for each of the following conductors:(i) a metal at constant temperature(ii) an ionic solution with inactive electrodes(iii) a gas (18)(i) axes and straight line 3through origin 3(ii) axes and straight line 3starting at v > 0 3(iii) axes and curve 3curve and plateau 3How would the graph for the metal differ if its temperature were increasing? (7)non linear / curve 7resistance increases (3)How would the graph for the ionic solution differ if its concentrationwere reduced? (7)slope of graph is less (stated or shown) 7resistance increases / less ions / less charge carriers (3)

2003 HL Q12(c)

How would you demonstrate an electric field pattern? (9)oil and semolina or seeds 3high tension / high voltage 3lines of semolina show field 3show direction of the electric field strength. (4)Arrow towards X 4

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2002 OL Q5(i) prevent (current) overload, prevent electrocution, safety, prevent fire 7reference to fuse/stops current (4)(j)

correct distribution of negative charge/all positive charge near pointed end (4)

2002 OL Q8Explain 2(2 3)potential difference: work done/energy 3moving (unit) charge 3unit (3)electric current: electron/charge 3flow/moving 3unit (3)

One difference 6 or 3(charge carried by) holes/two types of charge carriers/correct variation ofresistance with temperature 6conduction easier/better in metals (3)any reference to resistance/conduction (3)

How 2 3dope // add (impurity) 3(with) B/Al/Ga/In/group-3 element/extra holes/short of (lattice) electrons 3Draw 6 or 3

6reverse bias (3)Give 5 or 3rectifiers, transistors, diodes, thermistors, thermometers, radios/TV, etc. any two 5one use (3)

2002 OL Q12(c)Define 2 3charge 3divided by potential 3

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(3)explain the notation (3)What 2 3 +4(in diagram A) bulb lights 3(in diagram B) bulb does not light 3reverse order (3)explain: the capacitor conduct a.c./capacitor in A charging-discharging 4Demonstrate 4 3apparatus e.g. circuit, battery and capacitor 3procedure connect to battery to charge capacitor 3disconnect capacitor from battery, touch leads from capacitor 3observation spark observed/current flows 3a labelled diagram may merit marks

2002 HL Q5(h) cutting off supply / current / power 7( fault / difference in current between live and neutral /safety / protects against electrocution/ current in earth (wire) 3

2002 HL Q8

(ii) resistivity

resistance of a piece of material // 3unit length and unit area…………// explain R, A and l 3Demonstration of heating effectapparatus 3circuit 3way of detecting heat change 3result 3Reducing energy lostthicker cableslower resistivity / resistancehigher V (tension)EHT 5 2002 HL Q11(a) copper is a conductor. 4good 3

(b) force /FQ 4

per unit charge / explain symbols 3

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(c) experience (a large) force 7(d) ions act as charge carriers 7(moving / flowing 3)(e) electrons / current / charge / flow(s) to or from ground 4through conductor / copper / air 3(f) neutralises charged clouds 4conducting charge /lightning / current to earth 3(g) act as (lightning) conductors 7(current through body / injury / electrocution 3)(h) point effect / point discharge (or implied) 4( current) leakage / sparking / fire 3

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6th Year Physics: Electromagnetism Theory

2013 OL Q8(b)

(b) A magnetic field exists about a current-carrying conductor (i) What is a magnetic field?. 2×3 region / area /space 3 where iron is attracted / magnetic effect is felt 3 partial answer e.g. reference to force (3) (ii) Describe an experiment to show that a long straight wire carrying a current has a magnetic field. Sketch the magnetic field. 5×3 apparatus; source of current / battery / power supply 3 (plotting) compass // iron filings 3 procedure; complete the circuit / turn on the current 3 observation/conclusion: compass direction changes / iron filings rearrange 3 sketch the circular field (with correct direction) 3 accept valid alternatives full marks may be merited by a labelled diagram partial answer e.g. incomplete description (3) (iii) Give an application of the magnetic field due to a current 6 or 3 electromagnet, speaker, motor, induction coil, transformer, etc 6 partial answer e.g. an appliance containing a motor, etc. (3)

2013 HL Q11

(h) In some modern seismometers a magnet is attached to the mass and a coil of wire is attached to the frame. During an earthquake, there is relative motion between the magnet and the coil. Explain why an emf is generated in the coil. magnetic field passing through the coil // coil cuts 4 is changing // (magnetic) flux 3 (due to Faraday‟s law‟, 4 marks ; „due to Faraday‟s law of e.m.i.‟, 4 + 3)

2012 OL Q5

(g) Why does a magnet that is free to rotate point north? 7 or 4 earth’s magnetic field

7 partial answer

(4) (h) A transformer is used to change the voltage of an electrical supply. What is the principle of operation of a transformer? 7 or 4 change in magnetic flux induces an emf // correct reference to coils // e.m. induction

7 partial answer e.g. refers to Faraday / magnetic field /emf

(4)

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2012 HL Q5

(h) Sketch the magnetic field due to a current in a solenoid.uniform field inside solenoid / divergent field outside (–1 if incomplete field line)

7

2012 HL Q11

(c) What is electromagnetic induction?(when) a conductor/wire cuts magnetic flux

4an emf /voltage is induced

3( –1 if ‘magnetic’ not specified) (d) How is the output voltage of a wind turbine changed to 230 V a.c.?transformer 7

2011 OL Q9

(a) State Faraday’s law of electromagnetic induction. 3 x 3

partial answer e.g. Lenz’s law (3)

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A coil of wire is connected as shown in the diagram to a sensitive ammeter.

(i) What is observed on the meter when the magnet is moved towards the coil? 6 or 3needle deflected / moves 6partial answer

(3)(ii) What is observed on the meter when the magnet is stationary in the coil? 3no movement of needle

3(iii) Explain these observations 3 x 3emf // when current

3induced // flows / induced

3when change in magnetic field // needle moves

3partial answer

(3)(iv) How would changing the speed of the magnet affect the observations? 5 or 3more deflection if faster / less deflection if slower

5partial answer e.g. incomplete answer

(3)(b) Transformers can be used to step up or step down a.c. voltages.(i) What is meant by a.c.? 2 x 3alternating 3current

3electric current that reverses/changes its direction (at regular intervals)

(6)partial answer

(3)(ii) Draw a labelled diagram showing the structure of a transformer. 3 x 3

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2010 OL Q5

(g) Sketch the magnetic field surrounding a bar magnet 7 or 4correct diagram to show magnet, two field lines, correct direction on lines 7partial answer e.g. incomplete diagram (4)

2010 OL Q11

(a) Who discovered that an electric current can deflect a compass needle? 7Oersted /Hans / Christian 7(b) What did Arago discover? 7 or 4a wire carrying an electric current acted as a magnet / could attract iron filings 7partial answer e.g. incomplete answer (4)(c) What happens when currents flows in the same direction in two parallel wires?7 or 4the wires attract 7partial answer e.g. the wires move (4)(d) How could two parallel wires be made to repel each other? 7 or 4reverse one of the currents / current in opposite directions 7partial answer (4)(e) Draw a sketch of the apparatus Michael Faraday used to generate electricity 7 or 4correct diagram to include magnet, coil and meter 7partial answer e.g. incomplete diagram (4)

(f) What name is given to the generation of electricity discovered by

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Michael Faraday? 7 or 4electromagnetic induction 7partial answer e.g. induction (4)(g) What energy conversions that take place in Faraday’s experiment 7 or 4kinetic to electric 7partial answer e.g. one energy correct (4)(h) How does Faraday’s experiment show that a changing magnetic field isrequired to generate electricity? 7 or 4current stopped whenever the magnet was motionless // electricity is only generatedwhen the magnet or coil is moving 7partial answer e.g. incomplete answer (4)

2010 HL Q5

(g) State Faraday’s law of electromagnetic induction.

2009 OL Q9A magnetic field exists in the vicinity of a magnet(i) What is a magnetic field? 2 x 3area (where) 3magnet experiences force / magnet where it effects compass 3partial answer (3)marks may be obtained from a diagram

Describe an experiment to show the shape of the magnetic field due to a U-shaped magnet 4 x 3apparatus: U-shaped magnet, 3(plotting) compass / iron filings 3procedure: place piece of paper/perspex over the magnet an d sprinkle the iron filingsonto the paper // place a number of compasses near the magnet 3observation: note the shape of the magnetic field / collection of iron filings nearthe poles of the magnet 3marks may be obtained from a diagram(i) What happens to the compass when the switch is closed ? 6 or 3(needle) moves / deflects 6partial answer; e.g. current induced (3)marks may be obtained from a diagram(ii) What does this tell you about an electric current? 6 or 3it affects a compass, magnetic field, magnetic effect 6partial answer; e.g. electric current flows in the circuit (3)(iii) What happens to the compass when the switch is opened? 6 or 3(needle) moves / returns to original position 6partial answer; e.g. no current flows (3)The wire is then placed between the poles of a U -shaped magnet as shown in the diagram(iv)Describe what happens to the wire when a current flows through it 6 or 3wire moves / wire gets hot 6partial answer (3)(v) What would happen if the current flowed in the opposite direction? 6 or 3

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wire moves in opposite direction / magnetic field reverses 6partial answer. (3)(vi) Name two devices that are based on this effect 2 × 4(electric) motor, (moving coil) speaker, galvanometer etc any two 2×4

2008 OL Q12(d)What is electromagnetic induction? 2 × 3 emf / voltage / potential difference / current is induced 3 (due to) changing (magnetic) flux / field

//moving magnet 3 a diagram or example may merit full marks A magnet and a coil can be used to produce electricity. How would you demonstrate this? 4 × 3 + 4 apparatus: coil and magnet 3(galvano)meter 3meter attached to coil 3magnet moves relative to the coil 3 observation / conclusion: needle deflects / emf produced 4 The electricity produced is a.c. What is meant by a.c.? 2 × 3 alternating 3 current 3 a relevant explanation may merit 2 × 3

2008 HL Q8What is electromagnetic induction? conductor / wire /coil / loop cuts magnetic flux 3

emf / voltage induced 3 State the laws of electromagnetic induction.

(magnitude of the) induced emf is proportional to // 3

rate of cutting flux // notation (–1 per missing item) 3 induced current /emf in such a direction 3 as to oppose the change that causes it 3

underneath the magnet. Explain why the amplitude of the swings decreases rapidly. induced voltage/emf in copper 3current flows (in copper sheet) 3

(generating a) magnetic field 3 opposing motion of magnet 3 (‘damping occurs’ or ‘motion is damped’ …. 2 × 3) What is the main energy conversion that takes place as the magnet slows down?

kinetic/potential (energy)→ heat /electrical (energy) 6

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(award 3 marks for any relevant conversion)

2007 OL Q5(i) Draw a sketch of the magnetic field around a bar magnet 7 or 4Correct diagram to showmagnet, two field lines, correct direction on lines 7 partial answer e.g. incomplete diagram (4)

2007 Q12(d)Part(d)What is electromagnetic induction? 6 + 4emf / voltage / potential difference / current is induced(due to)changing (magnetic) flux / field // moving magnettwo lines correct 6 + 4one line correct (6)a diagram or example may merit full marksThe diagram shows a transformer.(i) Name the parts labelled A and B 2 × 3A = soft iron / core / (laminated) iron / former 3B = primary / input / coil 3(iii) Name a device that uses a transformer. 6 or 3mobile phone charger, television, power supply, washing machine, etc. any one 6partial answer (3)

2007 HL Q5(g) Why does a magnet that is free to rotate point towards the North?any reference to (earth’s) magnetic field / like poles repel / unlike poles attract 7(h) State the principle on which the definition of the ampere is based.force between (two) conductors // current-carrying conductor experiences a force 4carrying current // in a magnetic field 3[ correct formula … 7 marks]

2007 HL Q12(c)State Faraday’s law of electromagnetic induction.induced e.m.f. / voltage is proportional // E α dφ / dt or E = dφ / dt (accept E or V ) 3to rate of cutting / change of (magnetic) flux // correct notation 3

Describe an experiment to demonstrate Faraday’s law.apparatus coil, magnet, galvanometer or equivalent 3arrangement connect coil to G 3procedure move magnet towards coil 3

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-1 per missing item.A suitable diagram could merit 3 x 3Observation must be stated for final 3 marksobservation the faster the movement, the greater the deflection / (induced) voltage 3A resistor is connected in series with an ammeter and an ac power supply. A current flows in the circuit. The resistor is then replaced with a coil. The resistance of the circuit does not change.What is the effect on the current flowing in the circuit?current is reduced 4Justify your answer.back emf induced in coil ( -1 if back omitted) // coil has a self-inductance ( -1 if self omitted) // Lenz’s law reference 6

2006 OL Q10What is a magnetic field? 2 × 3 region / area /space 3 where iron is attracted / magnetic effect is felt 3 Describe an experiment to show the magnetic field due to a current in a solenoid. 4 × 3 apparatus: power source, closed circuit/ solenoid, compasses / iron filings any two 2×3 any one (3) procedure: turn on the current 3 observation/conclusion: compass direction changes / iron filings rearrange /arrows shown on field lines 3 accept valid alternatives a labelled diagram may merit full marks Give one use of an electromagnet. State one advantage of an electromagnet over an ordinary magnet. 6 + 3 electric bell / scrap yard crane / speaker / induction coil / doorbell / relay / etc. 6 partial answer e.g. in TV / radio (3) can be turned off / can be varied / can be stronger etc. 3 When the switch is closed the aluminium foil experiences an upward force. Name a device based on this effect. 6 or 3 (electric) motor / meter /speaker 6 partial answer e.g. radio (3) Describe what happens if 5 × 3 (i) the current flows in the opposite direction;

force / foil moves 3 downward / in the opposite direction 3

(ii) a larger current flows through the aluminium foil; greater / bigger 3

force / jump 3 (iii) the aluminium foil is placed parallel to the magnetic field. no force / no movement / nothing 3

2006 HL Q11(d) Why must the strings in the electric guitar be made of steel? (7) any reference to magnetism 7

(e) Define magnetic flux. (7) ( Ф = ) B A 4

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give notation 3 (f) Why does the current produced in a coil of the electric guitar vary? (7) (induced) emf / flux varies (due to amplitude of vibrating string) 7 (g) What is the effect on the sound produced when the number of turns in a coil is increased? (7) louder sound / greater (sound) intensity) / greater amplitude 7

2005 OL Q9What is a magnetic field? 2 × 3 region ( where) / space 3 magnetism is experienced // force is detected 3

Draw a sketch of the magnetic field around a bar magnet 6 + 3 diagram to show magnet two field lines correct direction on field lines any two 6 + 3 any one (6)

Describe an experiment to show that a current carrying conductor in a magnetic field experiences a force 4 × 3 apparatus: power supply/ battery / voltage, conductor, magnet any two 2 × 3 any one (3) procedure: set up the circuit / turn on the power supply / current 3 observation / conclusion: conductor moves / conductor deflects 3 accept valid alternatives a labelled diagram may merit marks State two factors on which the size of this force depends 2 × 3 current / I, strength of magnetic field / B, length of conductor / l, angle / θ any two 2 × 3 any one (3) accept voltage / resistance for current What is observed when the magnet is moving towards the coil? 2 × 3 needle / pointer / galvanometer // current 3 deflects // induced 3 Explain why this occurs 6 or 3 emf / voltage / current / electromagnetic induction 6 partial answer (3) Describe what happens when the speed of the magnet is increased 2 × 3 deflection / emf / current 3 greater / faster 3 Give one application of the effect shown in the diagram 5 dynamo, generator, induction motor, induction cooker, etc. any one 5

2005 HL Q5

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(f) Draw a sketch of the magnetic field due to a long straight current-carrying conductor. (7) (concentric) circles with arrows (indicating correct direction of field) 4 conductor with arrow (indicating direction of current in the conductor) 3 (no direction for field … -1. no direction for current … -1.)

2005 HL 12(b)Define magnetic flux. (6) Φ = BA 3 notation 3 State Faraday’s law of electromagnetic induction. (6) (magnitude of the) emf induced (in conductor) is proportional to // E (or e) ∝ (or = ) 3

the rate of change of (magnetic) flux (cutting the conductor) // 3

2004 Ol Q12(c)What is electromagnetic induction? 2 × 3emf / voltage / potential difference / current is induced 3(due to)changing (magnetic) flux / field // moving magnet 3Name another device that is based on electromagnetic induction 3dynamo, generator, induction motor, induction cooker, etc. any one 3

Name the parts of the transformer labelled A, B and C in the diagram 6 + 3A = primary / input (coil)B = secondary / output (coil)C = (iron) core / former any two 6 + 3any one (6)partial answer e.g. coil in A or B, reference to step-up (transformer) (3)

2004 HL Q5(i ) Give one use of the earth’s magnetic field. (7)compass / navigation / protective layer (around the earth) 7

2004 HL Q12(c)What is electromagnetic induction?Describe an experiment to demonstrate electromagnetic induction. (15)conductor cuts magnetic flux / (changing) magnetic flux cutting conductor 3emf induced 3arrangement: coil and galvanometer in series 3procedure: move magnet towards coil 3result: galvanometer indicates a current / G kicks 3

A light aluminium ring is suspended from a long thread as shown in the diagram. When astrong magnet is moved away from it, the ring follows the magnet. Explain why.What would happen if the magnet were moved towards the ring? (13)electromagnetic induction / emf induced in ring / changing flux or field 3current flows (in ring) 3in such a direction as to oppose change / ring follows magnet by Lenz’s law 3

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ring repelled / moves away 4

2003 OL Q5(h) any valid example e.g. kinetic to electric 7partial answer e.g. kinetic to chemical (4)(i) changing (a.c.) voltages / currents 7reference to changing // name of device (4)

2003 OL Q9

What is a magnetic field? 2 × 3region ( where) / space 3magnetism / force is experienced / detected 3Give one use of the earth’s magnetic field 5 h/mnavigation / compass // protection from solar winds 5

Describe how to demonstrate the magnetic effect of an electric current 4 × 3 + 6apparatus e.g. battery, circuit / conductor 2 × 3detector e.g. compass / iron filings 3procedure e.g. close the circuit / connect up stated or implied 3observation e.g. compass deflects 6a labelled diagram may merit markselectromagnet experiment // force on a current carrying conductor experiment fits the schemeDraw a sketch of the magnetic field around a straight wire carrying a current 3 × 3

current direction 3shape of magnetic field 3magnetic field direction consistent with the current 3relevant right hand rule stated or implied (2 × 3)Describe what happens when a current flows through the conductor 6 h/m(conductor / magnet) moves / jumps / deflects / vibrates 6Name two devices that are based on the effect demonstrated in this experiment 2 × 3loudspeaker, appropriate meters, (electric) motor any two 2 × 3

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What would happen if (i) a larger current flowed in the conductor? 3(i) bigger force / deflection // hotter // melts 3What would happen if (ii) the current flowed in the opposite direction? 3(ii) (conductor) moves / jumps / deflects in the opposite direction 3Current directionMagnetic fielddirectionCurrent carrying wire

2003 HL Q12(d)State the laws of electromagnetic induction. (12)

induced emf is // proportional to rate of change of flux // explain Φ and t 3direction of induced current / e.m.f. // minus sign included above 3opposes change producing it // significance of minus 3A small magnet is attached to a spring as shown in the diagram. The magnet is setoscillating up and down. Describe the current flowing in the circuit. (6)alternating // a.c. 6changing in magnitude (3)changing in direction (3)If the switch at A is open, the magnet will take longer to come to rest. Explain why. (10)no (induced) current 4no (induced) magnetic field (in coil) 3no opposing force / resistance 3

2002 OL Q9

What 3 3change in (magnetic flux)/field 3generates 3emf/E/I 3Describe 4 3apparatus e.g. coil, magnet, meter any one 3 all 2 3procedure e.g. move magnet/coil 3observation e.g. deflection on meter 3a labelled diagram may merit marksName 2 3computer, radio, TV, doorbell, washing machine, mobile phone chargers, etc.any two 23Name 3 3A primary/input coil 3B (iron) core 3C secondary/output coil 3A and C reversed maximum 2 3How 6 or 3laminated (core) 6

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(soft) iron (3)What 5 or 390%/0.9 of what goes in comes out //10% of the energy/power is lost 5any reference to loss of energy/power/eddy currents (3)

2002 OL Q12(d)

Lines 2 3diagram shows at least two lines between poles 3direction from N to S 3Describe 4 3apparatus power supply and conductor 3magnetic field 3procedure turn on power supply/current 3observation conductor moves/deflects 3a labelled diagram may merit marks

Two factors 2 3strength of magnetic field/Bsize of current flowing/Ilength of conductor in magnetic field/langle between conductor and magnetic field/_/sin_medium any two 2 3Device 4motor, (moving coil) meter, loudspeaker, named device which containsmotor e.g. electric shaver 4

2002 HL Q5

(i) magnetic flux density (B), Current (I), Length (l), angleany two 4 + 3

2002 HL Q12(c)em induction(induced) e.m.f (in a conductor / coil / wire) 3when magnetic flux / field changes 3Lenz’s lawdirection of (induced) current / voltage / emf 3opposes change causing it 3Why is current reduced?(back) e.m.f. in coil 3increased magnetic flux // increases 3increases back e.m.f. // self inductance 3reduces voltage / reduces current 3Applicationdimmer switch / smooth d.c. / tuning radios / braking trains

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/ damping in balances / induction coil 4

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6th Year Physics: Modern & Nuclear Theory

2013 OL Q5(c),(i),(j)

(c) Which of the following scientists is associated with the discovery of the structure of the atom?7 Einstein Rutherford Faraday Coulomb Rutherford 7

(i) What is the photoelectric effect? 7 or 4 emission of electrons when light (radiation) is incident 7 partial answer e.g. emission of electrons (4)

(j) Name one method for detecting radioactive particles. 7 or 4 Geiger-Muller tube, Geiger counter, solid state detector, cloud chamber, bubble chamber, GLE, photographic film, radioactive sensor, etc. 7 partial answer e.g. (radiation/film) badge (4)

2013 OL Q10

The image shows an X-ray photograph. (i) What are X-rays? 2×3 electromagnetic radiation // photons 3 high energy/frequency (low wavelength) 3 partial answer e.g. (3) (ii) State a property of X-rays that makes them suitable for medical use. 6 or 3 highly penetrating // selective absorbance 6 partial answer e.g. use such as to see broken bones // unsuitable property (3) (iii) Give a use, other than medical, for X-rays 6 or 3 airport security, X-ray telescopes/astronomy, weld/art inspection, thickness of metal, etc 6 partial answer e.g. general use such as industry/ agriculture (3)

In an X-ray tube a beam of electrons is used to produce X-rays (iv) Draw a labelled diagram showing the main parts of an X-ray tube 4×3

heater, cathode, anode, target, high voltage any three 3×3 detail e.g. correct arrangement / coolant / shielding/vacuum/extra item from previous line 3 partial answer (3) Note: no labels, deduct 1

(v) How are electrons produced in an X-ray tube? 2×3 heating // thermionic 3

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metal // emission 3 partial answer e.g. by the cathode, using current, etc. (3) (vi) What is the purpose of the high voltage in an X-ray tube? 6 or 3 accelerate electrons // give energy to electrons // give enough energy to produce X-rays 6 partial answer (3) (vii) What happens when the electrons hit the target in an X-ray tube? 6 or 3X-rays produced // target heats 6 partial answer (3) (viii) Name a suitable material for use as the target. 4 or 2 tungsten 4 partial answer e.g. (any named) metal (2) (ix) Give one safety precaution required when using X-rays 4 or 2 use a lead shield, protective clothing, lead glass, monitor dosage, reduce dosage, etc. 4 partial answer (2)

2013 OL Q12(d)

Part (d) Nuclear fission occurs in the reactor of a nuclear power station like the one shown in the photograph. (i) What is nuclear fission? 2×3 splitting (of large) nucleus 3 into (two) smaller nuclei // with release of energy/radiation // release of neutrons 3 partial answer e.g. definition of fusion (3) (ii) Name a fuel used in a nuclear reactor 6 or 3 plutonium / P, (enriched) uranium / U one correct 6 partial answer e.g. named reactor part such as boron steel, graphite (3) (iii) How can the reaction in a nuclear reactor be controlled? 6 or 3 correct reference to (control/boron) rods // refers to absorbing neutrons // vary (U) fuel 6 partial answer e.g. coolant (3) (iv) How is the energy produced in a reactor used to generate electricity? 6 or 3 heat exchanger // produces steam // turbine 6 partial answer e.g. generator (3) (v) State a hazard of nuclear reactors. 4 or 2 pollution /risk of nuclear contamination / fallout / difficulty of dealing with waste / health risk, dangerous, etc 4 partial answer e.g. war (2)

2013 HL Q5

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(h) Explain what is meant by the statement: “Zinc has a threshold frequency of 1.04 × 1015 Hz”. below this frequency e.m.r. /photons will not causeemission of electrons (from zinc surface) 4 + 3 (stated or implied) (or for a correct vice versa statement, 4 + 3) (i) Give one benefit of switching from fossil fuels to nuclear power for the generation of electricity. Explain your answer. more energy per kg / less carbon dioxide produced / production of useful radioisotopes etc. 4 explanation 3

2013 HL Q9

Define the becquerel. one disintegration per second 6 Name one device used to detect ionising radiations. GM tube / solid state detector etc. 3 Compare alpha, beta, and gamma emissions using the following headings: (a) penetrating ability, (b) deflection in a magnetic field. (a): gamma (most penetrating) > beta > alpha (least penetrating) 3 (b): alpha, beta deflected, gamma not deflected 3 alpha and beta deflected in opposite directions 3 The photograph shows one of the nuclear reactors at Chernobyl, where there was a fire in April 1986 that released large quantities of radioactive contaminants. Among the contaminants were iodine–131 and caesium–137, which are two of the unstable isotopes formed by the fission of uranium–235. Explain what happens during nuclear fission. large nucleus splits 3 into two smaller nuclei 3 with the emission of energy / neutrons 2 Iodine–131 decays with the emission of a beta-particle and has a half-life of 8 days. Write an equation for the beta-decay of iodine–131.

I → Xe+ e−10

54131

53131

(accept β for e) (1 mark for each correct number and symbol) 9 × 1

2012 OL Q5(j)

(j) What is the main source of energy in the sun? 7 or 4 hydrogen /nuclear / fusion 7 partial answer e.g. fission

(4)

2012 OL Q10

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A cathode ray tube and an X-ray tube are practical applications of thermionic emission. In these tubes thermionic emission releases electrons, which are then accelerated into a beam. An electron is a subatomic particle. Name another subatomic particle and give two of its properties. 3 x 3

The diagram shows a simple cathode ray tube. (i) Name the parts labelled A, B, and C in the diagram. 3 x 3 A- cathode / hot metal

3 B- anode 3 C- screen 3 3 correct labels mismatched

(2 x 3) partial answer e.g. 2 correct labels in incorrect order

(3) (ii) Give the function of any two of these labelled parts. 6 + 3 cathode emits (electrons) anode attracts/focuses /accelerates (electrons) screen (lights up to) show presence (of electrons) two correct 6 + 3 one correct (6) partial answer

(3) (iii) How can the beam of electrons be deflected? 6 or 3 electric field/electrode/magnetic field/magnet/X-Y plates

6 partial answer

(3) (iv) What happens at C when the electrons hit it? 6 or 3 lights up / fluorescence / spot

6 partial answer

(3) (v) Why is a vacuum needed in a cathode ray tube? 3 electrons not blocked / easier to pass through / electrons not absorbed

3

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In an X-ray tube, a beam of electrons is used to produce X-rays. Draw a sketch of an X-ray tube. 3 x 3 + 2

heater, cathode, anode, target, high voltage any three 3 x 3 detail e.g. correct arrangement / coolant / shielding/vacuum/extra item from previous line 2 partial answer

(3) Give one safety precaution taken by a radiographer when using an X-ray machine. 3 use a lead shield, protective clothing, lead glass, monitor dosage, reduce dosage, etc. 3

2012 OL Q11

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(a) What is meant by nuclear fission? 7 or 4 splitting nuclei // splitting (large) atoms

7 partial answer e.g. release of neutrons /energy / particles

(4) (b) What is radioactivity? 7 or 4 decay/splitting of a nucleus with the emission of particles/radiation

7 partial answer e.g. alpha/ beta / gamma / activity

(4) (c) What is a nuclear chain reaction? 7 or 4 a chain reaction is when the neutrons released during fission go on to split more atoms / or produce more neutrons

7 partial answer e.g. ongoing reaction

(4) (d) What is the function of the control rods? 7 or 4 adjust the power output // absorb neutrons, etc.

7 partial answer

(4)

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(e) What type of material are control rods made of? 7 or 4 boron / steel / silver / indium / cadmium, etc. // neutron absorber

7partial answer e.g. other named metal

(4) (f) Why did the reactor still generate heat even though the chain reaction had stopped? 7 or 4 because of the radioactive decay of the isotopes created during nuclear fission 7 partial answer

(4) (g) Why is it important to remove the heat generated? 7 or 4 to avoid over heating/ explosions / release of radiation

7 partial answer e.g. to protect the environment

(4) (h) Give one advantage of nuclear energy. 7 or 4 use less fuel for energy produced // does not pollute the air // fuel can be produced (in a breeder reactor) //no greenhouse gases, etc.

7 partial answer e.g. cheaper, plentiful

(4)

2012 HL Q8

Nuclear fission reactors are used as an energy source in many parts of the world, but it is only recently that the use of nuclear fusion as a possible power source is achieving some encouraging results.The ITER nuclear facility at Caderache in south-east France is a global collaboration that has been formed to “demonstrate that fusion is an energy source of the future”. It is expected to begin testing in 2016.Energy can be produced in a fusion reaction by combining a deuterium and a tritium nucleus as follows:

H12 + H1

3 → He24 +n+energy

(i) Distinguish between nuclear fission and nuclear fusion.fission: large nucleus splits

3into two smaller nuclei (of similar size)

3fusion: two small nuclei join

3to form a larger nucleus (–1 if ‘atoms’ referred to)

3(ii) What are the advantages of fusion over fission in terms of fuel sources and reaction products?(hydrogen) fuel (from the sea) is plentiful – (uranium for fission is scarce)

6no radioactive waste with fusion – (fission results in radioactive waste)

6

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(v) Fusion can only take place at very high temperatures. Explain why.nuclei must have very high speeds / energy if they are to combine/to overcome force of repulsion between the nuclei

52012 HL Q12(d)

(d) (i) Draw a diagram to show the structure of a photocell. (glass) tube/bulb 3vacuum (labelled) 3two electrodes 3

label at least one electrode 3

(ii) Describe an experiment to demonstrate how the current through a photocell can be increased.

apparatus: photocell, meter, light source, (power supply) 3

arrangement: as shown (–1 if incorrect polarity) 3procedure: bring light source closer (to photocell)

3observation: current in circuit increases

3(iii) Give an application of the photoelectric effect.controlling the flame in central heating boilers / automatic doors / fire alarms / photocells / photocopiers /light meters / photomultiplier tubes, etc.

any correct one 4

2011 OL Q10

Radon is a radioactive gas which emits alpha particles. Radon gas comes into houses through gaps in the floors. Exposure to radon gas can cause lung cancer.

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(i) What is radioactivity? 2 x 3( the spontaneous) breakup of the nucleus /atom

3(with the) emission of radiation/α / β/ γ/ energy

3partial answer

(3)

(ii) Name the other two types of radiation emitted by radioactive sources 6 or 5 or 3beta / β, gamma / γ two correct 6one correct (5)partial answer e.g. electrons, em radiation

(3)(iii) Describe an experiment to distinguish between the three types of radiation. 4 x 3apparatus: radioactive source (in lead container), magnetic / electric field,photographic (plate) any two 2 x 3any one (3)procedure: place the radioactive source in the electric/magnetic field

3observation: note three different marks on the photographic plate

3marks may be obtained from a diagramvalid alternatives(iv) List three properties of any one of the radiations. 3 x 3

The most stable isotope of radon has a half-life of 4 days.(v) What are isotopes? 2 x 3

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atoms of the same elements / same number of protons 3

with different mass numbers / different number of neutrons 3

partial answer e.g. reference to neutrons (3)

(vi) Why is it important to prevent radon gas entering your home? 5 or 3because it causes (lung) cancer / causes disease

5partial answer e.g. it is dangerous

(3)

(vii) If no more radon gas entered your home, how long would it be until oneeighth of the radon gas was left? 6 or 312 (days) 6partial answer e.g. implies 3 half-lives such as 64 days

(3)(viii) Give two uses of radioisotopes. 6 or 5 or 3medical, industrial, agriculture, smoke detectors, energy source, etctwo correct 6one correct (5)partial answer

(3)

2011 OL Q11

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(a) Who discovered the photoelectric effect? 7Hertz 7(b) Who explained the photoelectric effect? 7 or 4Einstein 7partial answer

(4)(c) What happens when light shines on certain metals? 7 or 4it transfers its energy to metal/ electrons // electrons are emitted

7partial answer e.g. transfer of energy

(4)(d) Why is a metal a good conductor of electricity? 7 or 4electrons are only loosely bound

7partial answer

(4)(e) Why does your skin feel warm when light shines on it? 7 or 4energy transferred from the light/radiation

7partial answer

(4)(f) In the photoelectric effect, what happens when the intensity of lightis increased? 7 or 4number of electrons released increases.

7

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partial answer (4)

(g) How can the speed of electrons emitted in the photoelectric effectbe controlled? 7 or 4change the frequency of the radiation

7partial answer

(4)

(h) Give one application of the photoelectric effect? 7 or 4photocell, alarms, photocopiers, light meters, photodiodes, etc

7partial answer e.g. TV, solar cell, non specific use

(4)

2011 OL Q12(d)

(d) The diagram shows an arrangement used to investigate the structure of the atom.During the investigation alpha-particles were fired at a thin sheet of gold foil in a vacuum.

(i) What are alpha particles? 6 or 3consist of two protons and two neutrons // helium (nucleus)

6partial answer e.g. radioactive particles, any alpha property

(3)(ii) What happened to the alpha particles in the experiment? 6 or 3some deflected, some un-deviated, some reflectedtwo correct 6one correct (3)(iii) What did the experiment reveal about the structure of the atom? 6 or 3mainly empty space // (positive) nucleus at centre

6partial answer

(3)(iv) Name the scientist who designed the experiment? 6 or 3Rutherford 6partial answer e.g. other named nuclear scientist

(3)

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(v) Name a suitable detector of alpha-particles. 4 or 2GM tube, solid state detector, cloud chamber, ionisation tube, ZnS screen,gold leaf electroscope, photographic film, etc.

4partial answer e.g. (monitor) badge

(2)

2011 Hl Q5

(g) The physicist Robert Millikan is usually associated with what physical quantity?charge (on the electron) / 1.6 × 10–19 C

7(reference to ‘oil drop’/ ‘electron’ experiment … 4 marks)

(h) What property of light controls the current in a photocell?(light) intensity/ brightness / photoelectric effect / any valid answer

7

(i) What is the role of neutrons in a nuclear reactor?to cause (nuclear) fission / to initiate reaction / any valid answer

7

2011 Hl Q11

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(b) Most of the energy emitted in a CFL is in the form of ultraviolet radiation.How is this changed to white light?UV (radiation) absorbed (by electrons) in the fluorescent coating (which)

4emits visible (white) light / photons of lower energy

3 (d) How does an electron in an atom of the fluorescent coating emit a photon?electron absorbs UV photon and jumps to higher energy level

4(then) drops back (to lower level) emitting a photon

3(e) Why does the fluorescent coating in a CFL get warm during use?due to absorption // energy difference

4(of) UV photons / energy // between incident and emitted photons

3

2011 Hl Q12(d)

(d) In the manufacture of newsprint paper, heavy rollers are used to adjust the thickness of the movingpaper. The paper passes between a radioisotope and a detector, and a pair of rollers, as shown.

(i) Name a suitable detector.solid state detector / GM tube (linked with a ratemeter/scaler)

6

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(ii) Describe how the reading on the detector may vary as the paper passes by.(count rate) would decrease

3with increasing paper thickness

6(or vice versa)(iii) Why would the radioisotope Am-241, which emits alpha-particles, not be suitable for thisprocess?paper would (easily) block alpha-particles / alpha-particles have poor penetrating power 4

2010 OL Q5

(j) What type of nuclear reaction occurs in a nuclear power station? 7 or 4fission 7partial answer e.g. fusion (4)

2010 OL Q10

X-rays are produced when high speed electrons collide with a target in an X-ray tubeas shown in the diagram(i) What process occurs at the filament A? 6 or 3thermionic emission / release of electrons // heating 6partial answer e.g. incomplete answer (3)(ii) Name a substance commonly used as the target B 6 or 3tungsten / molybdenum 6partial answer e.g. metal / named metal (3)(iii) Give three properties of X-rays 3 3(electromagnetic) waves / have short wavelength, ionise, penetrate, no mass,no charge, effect photographic film, cause fluorescence, diffraction, etc.three correct 3x3two correct (2 3)one correct (3)(iv) Give two uses of X-rays 2 × 3specific medical use e.g. X-ray photo, photo organs, destroy cancerous cellsspecific industrial use e.g. detect cracks in metals, determine thickness of materialstwo correct 2 3one correct (3)partial answer e.g. general use such as medicine/industry/photos (3)(v) State the function of the part marked C 5 or 3protection / shielding 5partial answer e.g. maintain a vacuum (3)The photoelectric effect can be regarded as the inverse of X-ray production(vi) What is meant by the photoelectric effect? 2 3emission of electrons (from the surface of a metal by) 3(electromagnetic) radiation / light (of a suitable frequency) 3(vii) Describe an experiment to demonstrate the photoelectric effect 4 3apparatus: (gold leaf) electroscope, 3

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UV lamp 3procedure: place a zinc plate on the cap of the electroscope / charge the electroscopenegatively / shine the UV lamp on the zinc plate. 3observation //conclusion: the leaf collapses // electrons emitted 3marks may be obtained from a diagramaccept valid alternatives

(viii) Give two applications of the photoelectric effect 2 3burglar alarms, automatic doors, central heating control, film sound track, etc.two correct 2 3one correct (3)

2010 OL Q12(d)

What is radioactivity? 2 3disintegration/decay of nuclei/atoms 3with emission of radiation/energy /α / β / γ 3The diagram shows a shielded radioactive source emitting nuclear radiation.(i) How do you know that the source is emitting three types of radiation? 3one type stopped by the paper, 2nd by the aluminium and the 3rd by the concrete 3(ii) Name the radiation blocked by each material 2 3paper blocks alpha / α,aluminium blocks beta/ β,concrete blocks gamma/ γtwo correct 2 3(iii) Give one danger associated with nuclear radiation 3cancer, radiation sickness, ionises/kills/damages cells, etc. one correct 3(iv) State two precautions that should be taken when handling radioactivesubstances 4 or 2use tongs, wear gloves, do not point at body, etc two correct 4one correct (2)(v) Give two uses for radioactive substances 2 3medical / energy source / industrialtwo correct 2 3one correct (3)

2010 HL Q5

(i) Name the naturally occurring radioactive gas which seeps into buildings fromunderground rocks and which can cause lung cancer.radon (gas) 7

2010 HL Q9What is thermionic emission?the emission of electrons 3

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(from the) surface of a hot metal 3

X-rays are produced when high-energy electrons collide with a target.Draw a labelled diagram of an X-ray tube.

vacuum 3cathode 3target / anode 3high (accelerating anode) voltage or H.T. / shielding / cooling / low (cathode) voltage or L.T. 3

What are X-rays and how do they differ from light rays?what: electromagnetic radiation / photons / quanta of energy 6high frequency / short wavelength / high energy 3how: x-rays penetrate matter / cause ionization / any valid comparative property 3Give two uses of X-rays.(medical) analysis of bone structure/ luggage scanners (at airports) / any specific medical,industrial or security use, etc. any two 2×3When electrons hit the target in an X-ray tube, only a small percentage of their energy isconverted into X-rays. What happens to the rest of their energy and how does this influencethe type of target used?converted to heat 6target material must have (very) high melting point / (specific example, e.g.) tungsten 3

2010 HL Q12(b)(i) Identify the element X.Kr / krypton 6(iii) What is a chain reaction?self-sustaining reaction / reaction where fission neutrons produce further fission(giving more neutrons) etc./ clear diagrammatic representation 6

Give one condition necessary for a chain reaction to occur.mass of fuel present exceeds the critical mass / at least one of the neutrons releasedmust cause fission of another nucleus 3

(iv) Give one environmental impact associated with a nuclear reactor.toxic /radioactive waste, exposure to radiation, etc. 4

2009 Q5(h) What are isotopes? 7 or 4elements with different mass number 7partial answer; e.g. mention of atoms / elements (4)

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(i) Give one application of the photoelectric effect 7 or 4burglar alarms, automatic doors, control of burners in central heating, soundtrack in films, etc one correct 7partial answer; e.g. definition (4)

(j) State two properties of X-rays 7 or 4electromagnetic waves, have short wavelength, cause ionisation , penetratematerials, no mass, no charge, effect photographic film, diffraction, etc.two correct 7one correct (4)

2009 OL Q10Radioactive elements are unstable and decay with the release of radiationHow would you detect radiation? 6 or 3GM tube, solid state detector, cloud chamber, ionisation tube, ZnS screenscintillation counter, gold leaf electroscope, photographi c film, etc. one correct 6partial answer (3)Name the three types of radiation 3 × 2alpha / α 2beta / β 2gamma / γ 2(i) Which radiation is negatively charged? 2beta / β 2(ii) Which radiation has the shortest range? 2alpha / α 2(iii) Which radiation is not affected by electric fields? 2gamma / γ 2Nuclear fission occurs in a nuclear reactor(iv) What is nuclear fission? 2 × 3splitting (of large) nucleus) 3into (two) smaller nuclei / with release of energy / release of neutrons 3partial answer; e.g. definition of fusion (3)(v) What is the role of neutrons in nuclear fission? 6 or 3split nucleus, makes nucleus unstable, causes fission one correct 6partial answer; e.g. neutrons fired at/hit nucleus (3)

(vi) Name a fuel used in a nuclear reactor 6 or 3plutonium / P, (enriched) uranium / U, thorium / Th one correct 6partial answer; e.g. named reactor part (3)(vii) In a nuclear reactor how can the fission be controlled or stopped? 6 or 3correct reference to (control/boron) rods // refers to slowing down neutrons 6partial answer (3)(viii) How is the energy produced in a nuclear reactor used to generate electricity? 6 + 3(energy produced) converted to heat /(this is used to) generates steam 6(which) drives generator /turbine 3partial answer (3)(ix) Give one advantage and one disadvantage of a nuclear reactor as a source

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of energy 5 or 3advantage; abundant fuel / cheap fuel / no greenhouse gases / no global warming , etc.disadvantage; risk of nuclear contamination / fallout / difficulty of dealing with waste /dangerous, etc.advantage and disadvantage for fission or fusion reactor both correct 5advantage and disadvantage one correct (3)

2009 OL Q12(d)

The diagram shows a simple cathode ray tube. Thermionic emission occurs at plate A(i) What is thermionic emission? 2 x 3emission of electrons 3from the hot surface / from a hot metal 3partial answer (3)(ii) What are cathode rays? 2 x 3(stream of) high speed 3electrons 3partial answer (3)(iii) Why is there a high voltage between A and B? 2 x 3to accelerate / attract 3(the beam of) electrons 3partial answer (3)(iv) What happens to the cathode rays when they hit the screen C? 6 or 3converted to light // bright dot (on screen) 6partial answer (3)(v) Give a use for a cathode ray tube 4 or 2TV/computer/screen/oscilloscope, X-rays, etc. 4partial answer (2)

2009 HL Q5(i) How are X-rays produced?accelerated / fast moving electrons 4strike a (heavy) metal (target) / anode 3

2009 HL Q8What is a photon?packet/bundle/quantum 3of (light) energy/electromagnetic radiation 3An investigation was carried out to establish the relationship between the current flowing in a photocell and the frequency of the light incident on it. The graph illustrates the relationship.

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Draw a labelled diagram of the structure of a photocell.(wire) anode / electrode 3(cylindrical) cathode / electrode 3vacuum 3(glass) casing 3(–1 for each missing label)Explain why a current does not flow in the photocell when the frequency of the light is lessthan 5.2 × 1014 Hz.frequency less than 3threshold frequency 3The relationship between the current flowing in a photocell and the intensity of the light incident on the photocell was then investigated. Readings were taken and a graph was drawn to show the relationship.Draw a sketch of the graph obtained. How was the intensity of the light varied?

labelled axes 3correct shape 3vary distance from light source to photocell 5

What conclusion about the nature of light can be drawn from these investigations?light is made up of photons / bundles of energy// light has a corpuscular nature // light has not got a wave nature 6

2009 HL Q12(d)Smoke detectors use a very small quantity of the element americium -241.Alpha particles are produced by the americium-241 in a smoke detector.(i) Give the structure of an alpha particle.

2 protons and 2 neutrons // helium nucleus // 3 (ii) How are the alpha particles produced?(americium) is radioactive / unstable /disintegrates /undergoes α-decay 6

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(iii) Why do these alpha particles not pose a health risk?very short range / poor penetrators / neutralised (to form helium)trapped within smoke detector (any one reason) 4Explain why americium-241 does not exist naturally.not a member of a decay series / half life is short (w.r.t. age of universe - state/imply)/ any reference to synthetic/artificial / no natural parent (any one) 6

2008 OL Q5(i) State two properties of X-rays 7 or 4 electromagnetic waves, have short wavelength, cause ionisation, penetrate materials, no mass, no charge,

effect photographic film, etc. two correct 7 one correct (4) (j) What is nuclear fusion? 7 or 4 release of energy by joining of two (light) nuclei 7 partial answer e.g. release of energy /joining nuclei / explosions in sun (4) diagram may merit full marks

2008 OL Q10Give two properties of an electron 9 or 6 (negatively) charged; deflected by electric fields; deflected by magnetic fields; fundamental particle; 1.6 x 10-19; small mass; outside nucleus; etc two correct 9 one correct (6)

The diagram shows the arrangement used by Rutherford to investigate the structure of the atom. During the investigation he fired alpha-particles at a thin sheet of gold foil in a vacuum.

(i) What are alpha-particles? 9 or 6 or 3 consist of two protons and two neutrons // helium (nucleus) 9 consist of protons and neutrons // radioactive particles (6)partial answer e.g. any alpha property (3) (ii) Describe what happened to the alpha-particles during the experiment 9 or 6 or 3 most went straight throughsome deflected by various amountssome bounced backtwo lines correct 9 one line correct (6)partial answer e.g. reference to proton/neutron (3)

(iii) What conclusion did Rutherford make about the structure of the atom? 9 or 6 or 3 mainly empty spacedense nucleus central positive area (nucleus) two lines correct 9one line correct (6)partial answer (3)

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(iv) How are the electrons arranged in the atom? 9 or 6 or 3 orbit nucleus 9 on outside // moving (6) partial answer (3) (v) Name a device used to detect alpha-particles 6 or 3 GM tube, solid state detector, cloud chamber, ionisation tube, ZnS screen scintillation counter, gold leaf

electroscope, photographic film, etc. one correct 6 partial answer e.g. monitor badge (3) (vi) Why was it necessary to carry out this experiment in a vacuum? 5 or 3

alpha particles would be stopped by a few cm of air 5 partial answer (3)

2008 OL Q12Part (c)

What is the photoelectric effect? 2 × 3emission of electrons 3(when) light (hits a metal) 3

A photocell is connected to a sensitive galvanometer as shown in the diagram. When light from the torch falls on the photocell, a current is detected by the galvanometer. (i) Name the parts of the photocell labelled A and B. 2 × 3

A = (photo)cathode 3

B = (photo)anode 3

(in reverse order –1)

(ii) How can you vary the brightness of the light falling on the photocell? 6 or 3move it towards / away from the photocell // use a different torch 6 partial answer (3) (iii) How does the brightness of the light effect the current? 4 or 2 brighter the light the greater the current // dimmer the light the less the current 4 partial answer e.g. more current (2) (iv) Give a use for a photocell. 6 or 3 (burglar) alarms, automatic door, control burners in heating systems, safety switches, light meters, solarcells, sound track in film, etc one correct 6 partial answer e.g. non-specific use (3)

2008 HL Q5(i) Name an instrument used to detect radioactivity. What is the principle of operation of this

instrument? GM-tube // Cloud/ionisation chamber // solid state detector 4 ionization // condensation/ cloud formation/ionization // (formation) of ion-pairs 3

2008 HL Q11(e) What is the photoelectric effect?

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emission of electrons from metal surface 4 when light /radiation (of suitable frequency) falls on it 3 (f) Why was the quantum theory of light revolutionary? light travels in /consists of packets of energy / photons / quanta // light has a particle nature (as well as a wave nature) // (the theory suggested) E = h f / E α f // in conflict with wave theory 7

2008 HL Q12(c)(c) In 1939 Lise Meitner discovered that the uranium isotope U–238 undergoes fission when struck by a slow neutron. Barium–139 and krypton–97 nuclei are emitted along with three neutrons. Write a nuclear reaction to represent the reaction.

In a nuclear fission reactor, neutrons are slowed down after being emitted. Why are the neutrons slowed down? (only) slow neutrons cause fission / to prevent (radiative) capture 6 How are they slowed down? (they collide with) heavy water / a moderator / graphite 3 Fission reactors are being suggested as a partial solution to Ireland’s energy needs. Give one positive and one negative environmental impact of fission reactors. positive: no CO2 emissions / no greenhouse gases / no gases to result in acid rain / less dependence on fossil fuels / etc. negative: radioactive waste / (potential for ) major accidents / etc. (any order) 4+3

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2007 OL Q10What are X-rays? Give one use for X-rays. 2(6 or 3)X-rays: electromagnetic waves // high energy radiation 6partial answer e.g. stated property such as ionisation / radiation (3)Use: to photograph bones/ internal organs, to treat cancer, to detect flawsin materials, to determine the thickness of materials, etc. any one 6partial answer e.g. reference to photograph / medicine / industry, etc (3)The diagram shows a simple X-ray tube.Name the parts labelled A, B and C. 6 + 3 + 3A = Cathode / (heating) coil / filamentB = Anode / targetC = Lead / shieldall three correct 6 + 3 + 3two correct (6 + 3)one correct (6)A and B mismatched -3 marks(i) Explain how the electrons are emitted from A. 2 × 6thermionic / heating 6emission / coil 6partial answer e.g. reference to voltage (6)(ii) What is the purpose of the high voltage supply? 2 × 3to accelerate/ pull / attract /give more energy to // to produce 3electrons // cathode rays / X -rays 3(iii) What happens when the electrons hit part B? 4X-rays are emitted // energy released (as X-rays) // gets hot 4(iv) Name a suitable material to use for part B. 6 or 3target named metal e.g. tungsten / molybdenum / titanium, etc. 6anode named metal e.g. copper, etc. (6)partial answer (3)(v) Give one safety precaution when using X-rays 4use a lead shield, lead apron, lead glass, monitor dosage, reduce dosage, etc. any one 4

2007 OL Q11(a) What is radioactivity 7 or 4decay of nuclei with the emission of radiation / energy /α / β / γ 7partial answer e.g. emission of radiation /α / β / γ // radioactive property (4)decay of unstable nuclei (7)(b) What is the source of radon? 7 or 4uranium, radium, rocks, soil any one 7partial (4)(c) Name a detector of radiation 7Geiger –Muller tube, ionisation chamber, cloud chamber, GLE, etc. any one 7(d) How does radon enter a building? 7through small cracks, through the floor, through gaps around pipes any one 7(e) How can the build-up of radon in the home be prevented? 7 or 4by installing a radon membrane, installing a depressurising unit, sealing cracks,sealing gaps, having good ventilation, etc. any one 7partial (4)(f) Why is radon dangerous? 7 or 4can damage lung tissue // can cause cancer 7partial (4)(g) Why is radon harmless in the open air? 7 or 4diluted (to harmless concentrations) 7partial (4)

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(h) Name a radioactive element other than radon 7 or 4uranium, radium, plutonium, carbon 14, etc. any one 7partial (4)

2007 HL Q5(i) How are electrons accelerated in a cathode ray tube?( by a large) p.d /voltage / H.T / E.H.T./ electric field 7

2007 HL Q11(a) What is nuclear fission?disintegration / break-up / splitting of a large nucleus 4into two smaller nuclei (+ neutrons + energy) 3

( -1 if atoms used; -1 if no comparative term used) (c) At present, why is a fission reactor a more viable source of energy than a fusion reactor?(fission) can be (more) easily controlled / easier to initiate reaction or vice versa 7(d) Deuterium is an isotope of hydrogen; what is an isotope?atoms of the same element // atoms having the same atomic number / number of protons 4having a different number of neutrons / (atomic) mass (or weight) / mass number 3(e) What is the function of a moderator in a fission reactor?to slow down (fast)neutrons (to facilitate fission) 7(h) What is the source of the sun’s energy?fusion (reaction) / hydrogen (gas) 7( “nuclear reaction” …. 4 marks)

2007 HL Q12(d)Explain the term half-life.

time // 3for half (the radioactive nuclei in a sample) to decay / for activity (of a sample) to be halved // λ a constant 3A sample of carbon is mainly carbon-12 which is not radioactive, and a small proportion of carbon-14 which is radioactive. When a tree is cut down the carbon-14 present in the wood at that time decays by beta emission.Write a nuclear equation to represent the decay of carbon-14.

3 x 3 ( accept e in lieu of β …. –1 for each error)

Name an instrument used to measure the activity of a sample. What is the principle of operation of this instrument?Geiger Counter / GM tube: ( gas is) ionised (and a pulse of charge/current flows)ratemeter : average number of particles / current detected or displayedscaler: total number of particles / pulses of charge is counted or displayedsolid state detector: electron-hole pairs createdetc. (for any one instrument + principle) 6 + 1page

2006 OL Q5(j) Give two properties of the electron. 7 or 4 (small) mass /9.1×10-31 kg, (negative) charge/1.6× 10-19, orbits the nucleus,

outside the nucleus, deflected by electric / magnetic fields, etc. any two 7 any one (4)2006 OL Q9

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(i) What is meant by fission? Name a material in which fission occurs. 2 × 3 + 6 splitting / break up nucleus (into two) 3 releasing energy / releasing neutrons / releasing radiation / into 2 smaller (nuclei) 3 Uranium / U // Plutonium / Pu 6 (ii) Describe how a chain reaction occurs in the fuel rods. Explain how the chain reaction is controlled. 5 × 3 neutron 3 splits a nucleus 3 releasing more neutrons 3 partial answer e.g. continuous fission (3) a labelled diagram may merit full marks control rods // moderator 3 move up / move down /absorb neutrons // slows down neutrons 3 (iii) What is the purpose of the shielding? Name a material that is used as shielding. 4 × 3 prevent // protect 3 radiation (escaping) // humans / environment 3 concrete, lead any one 2×3 partial answer e.g. iron / named metal (3) (iv) Describe what happens to the coolant when the reactor is working. 5 or 3 absorbs heat / gets hot 5 partial answer e.g. it circulates / regulates temperature (3) (v) Give one effect of a nuclear fission reactor on the environment. 6 or 3 pollution / nuclear waste 6partial answer e.g. dangerous (3) (vi) Give one precaution that should be taken when storing radioactive materials. 6 or 3 store in lead / use a tongs when handling / use safety signs / locked room, etc. 6 partial answer e.g. store in a safe place (3)

2006 OL Q12(c)Explain why the gold leaf deflects when the zinc is given a negative charge. 6 + 3 like charges / electrons repel two correct 6+3 one correct (6) partial answer (3) UV radiation is then shone on the zinc and the gold leaf falls. Explain why. 3 × 3 electrons / charge 3 (are) emitted from 3 zinc / metal (cap) / leaf 3 partial answer (3) What is observed when the experiment is repeated using IR radiation? 6 or 3 leaf does not collapse / nothing changed 6 partial answer e.g. nothing (3) Give one application of the photoelectric effect. 4 photocell / burglar alarms / smoke alarms / automatic doors/ machine safety switches etc. 4

2006 HL Q5(i) Describe the Bohr model of the atom. (7) nucleus (any reference) 4 electrons in orbit / shells / energy levels 3

2006 HL Q8Distinguish between fission and fusion. (12) fission is the splitting of a (large) nucleus 3

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into two similar sized / smaller nuclei (with the emission of energy and neutrons) 3 fusion is the joining of two (small) nuclei 3 to form a larger nucleus (with the emission of energy) 3 The core of our sun is extremely hot and acts as a fusion reactor. Why are large temperatures required for fusion to occur? (5) nuclei are positively charged 3 (Coulomb / force of ) repulsion must be overcome / large energy necessary to join them together 2

In the sun a series of different fusion reactions take place. In one of the reactions, 2 isotopes of helium, each with a mass number of 3, combine to form another isotope of helium with the release of 2 protons.

Write an equation for this nuclear reaction. (12)

Controlled nuclear fusion has been achieved on earth using the following reaction. What condition is necessary for this reaction to take place on earthlarge (initial) temperature / energy (required to start the reaction) 3 Give one benefit of a terrestrial fusion reactor under each of the following headings: (i) fuel; (ii) energy; (iii) pollution. (9) fuel: plentiful / readily available / cheap 3 energy: vast (energy released) / more (energy released gram for gram than from other sources) 3 pollution: no / little (radioactive) waste ; no / few greenhouse gases (any one of these) 3

2006 HL Q12(d)(d) The first Nobel Prize in Physics was awarded in 1901 for the discovery of X-rays. What are X-rays? Who discovered them? (9) electromagnetic radiation 3 of short wavelength / high frequency 3 Rontgen 3 In an X-ray tube electrons are emitted from a metal cathode and accelerated across the tube to hit a metal anode. How are the electrons (i) emitted from the cathode; (ii) accelerated? (6) by thermionic emission / by heating the cathode 3 by the (E.) H.T / high voltage (between the anode and cathode) 3

2005 OL Q5(i) What is the photoelectric effect 7 or 4 (emission of) electrons due to light / radiation

7

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partial answer (4)

(j) Name a material used as shielding in a nuclear reactor 7 or 4 lead / concrete

7 partial answer e.g. metal (4)

2005 OL Q10Give two properties of the electron 6 + 3 negative, small mass, orbits/outside nucleus, no internal structure, lepton any two 6 + 3 any one (6) Name another sub atomic particle 3 proton, neutron, positron, muon, baryon, any other correct “particle zoo” particle 3 Name the parts labelled A, B and C 6 + 2 × 3 A = (heating) filament/coil, B = cathode, C = anode 6 + 2 × 3 any two correct (6 + 3) any one correct (6) correct names mismatched deduct 3 gives the function of two or more instead of naming maximum 6 (i) Explain how the electrons are emitted from A 6 + 3

current heats (filament electrons emitted) two lines 6 + 3 one line (6) thermionic emission (6 + 3)

(ii) What causes the electrons to be accelerated across the tube? 2 × 3 high / positive / anode 3 voltage 3

(iii) What happens when the electrons hit the screen? 6 or 3 light (is emitted) 6

partial answer (3) (iv) How can a beam of electrons be deflected? 2 × 3

electric / magnetic // X / Y / + / - 3 field // plates 3

(v) Give one use of a cathode ray tube 5 or 3 TV / CRO / monitor / ECG 5

partial answer (3)

2005 OL Q11(g) How does the Sun produce heat and light? 7 or 4

nuclear reactions / fusion / E = mc2 7 partial answer e.g. reference to mass, radioactivity, fission, hydrogen, burning gases (4)

(h) In Einstein’s equation E = mc2, what does c represent? 7 or 4 speed of light / 3 × 108 7

partial answer e.g. speed (4)

2005 OL Q12(d)What is meant by radioactivity? 2 × 3 break up of nucleus / atoms 3 emission of radiation /energy // emission of α /β /γ 3 decay of unstable nuclei (2 × 3) Name a detector of radioactivity 6 or 3 Geiger-Muller tube, Geiger counter, solid state detector, cloud chamber,

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bubble chamber, photographic film, radioactive sensor, etc. any one 6 partial answer e.g. badges (3)

Explain the term half life 2 × 3 time taken 3 for half (radioactive) nuclei / element / substance / atoms to decay // activity to half 3 Give one use of a radioactive isotope 4 or 2 detect disease, cure cancer, sterilise instruments, smoke detectors, detect leaks, trace flow of liquids, carbon dating, etc. any one 4 partial answer (2)

2005 HL Q5(i) How are electrons produced in an X-ray tube? (7) at the (heated) cathode / filament 4 thermionic emission occurs 3

2005 HL Q8Nuclear disintegrations occur in radioactivity and in fission. Distinguish between radioactivity and fission. (12) radioactivity is the disintegration of an (unstable) nucleus 3 with the emission of α / β / γ / radiation 3 fission is the splitting of a (large) nucleus 3 into two similar sized / smaller nuclei with the release of energy and neutrons 3 Give an application of (i) radioactivity, (ii) fission. (6) (i) smoke detectors, carbon dating, tracing leaks, medical (cancer treatment, sterilising), etc. 3 (ii) generating electrical energy / power, bombs 3 Radioactivity causes ionisation in materials. What is ionisation? (3) the charging of a (neutral) atom / (when) atom loses (or gains) electron(s) / atom (formed) with unequal number of + and - (charges) 3 Describe an experiment to demonstrate the ionising effect of radioactivity. (12) Apparatus: radioactive source and charged (gold leaf) electroscope 3 Procedure: bring radioactive source close to the cap 3 Observation: leaves collapse 3 Conclusion: as charge leaks away through ionised air / electroscope neutralised by ionised air 3 Cobalt−60 is a radioactive isotope with a half-life of 5.26 years and emits beta particles.

(i) Write an equation to represent the decay of cobalt−60. (9)

(each incorrect item .. –3) 3×3 (numbers consistently inverted or placed to the left, right or alternate side of symbol, acceptable.)

2005 HL Q12(d)One hundred years ago, Albert Einstein explained the photoelectric effect. What is the photoelectric effect? (6) emission of electrons from the surface of a metal 3 when light of suitable frequency / energy shines on it 3 Write down an expression for Einstein’s photoelectric law. (9) hf = φ + ½mv2 (each incorrect item … -3) 3×3 Summarise Einstein’s explanation of the photoelectric effect. (9)

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photons (of light) / quanta / packets (or bundles) of energy 3 all of energy from one photon is given to one electron 3 energy must be greater than work function of metal for P.E.E. to occur / for electron to escape 3

Give one application of the photoelectric effect. (4) sound track in film, photography, counters, photocell, burglar alarm, automatic doors, etc. 4

2004 OL Q5(i) Which one of the following is emitted from a metal surface 7electrons 7(j) What is nuclear fission? 7 or 4break up of nucleus / atom 7partial answer e.g. release of energy / neutrons (4)diagram may merit full marks

2004 OL Q10What is radioactivity? 6 + 3disintegration / decayof nuclei / atomsemission of radiation / energy /α / β / γ any two lines 6 + 3any line (6)Name the French physicist who discovered radioactivity in 1896 6 or 3(Henri) Becquerel / Curie 6partial answer e.g. named nuclear scientist (3)Name the radiations labelled X, Y and Z in the diagram 6 + 3 + 3(i) X = alpha / α (ii) Y = gamma / γ (iii) Z = beta / βthree correct 6 + 3 + 3two correct / all radiations named correctly but mismatched maximum mark (6 + 3)any one correct (6)Which one is the most ionising? 6alpha / α / X 6Name a detector of ionising radiation 6GM tube / / cloud chamber / ionisation tube /scintillation counter / gold leaf electroscope / solid state detectorphotographic film, ZnS screen, etc. any one 6Outline the principle on which the detectors works 6 or 3ionisation, blackens film, fluorescence 6partial answer e.g. principle inconsistent with the named detector (3)(i) Two precautions that should be taken when dealing with radioactive sources 5 or 3(thick) shielding, long life (containers), never eat / drink / smoke in vicinity,security (against theft), isolating, use protective clothing / gloves / use a tongswhen handling, labelling, minimise time spent using radioactive source,keep as far away from source as possible, use warning signs, etc. any two 5any one (3)

(ii) One use of a radioactive source 3carbon dating, radiotherapy, sterilising medical equipment, killing bacteria in foodfinding leaks in pipes and seals, checking thickness of materials, smoke alarm

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tracers in medicine / agriculture, energy source e.g. pacemakers, etc. any one 3(iii) One harmful effect of radiation 3cancer, skin burns, sickness, cataracts, cause sterility, damage to crops,genetic, etc. any one 3

2004 OL Q12(d)What are X-rays? 2 × 3electromagnetic / stated property e.g. high energy 3radiation / waves / rays 3

How are electrons emitted from the cathode? 6 or 3thermionic emission / heat 6partial answer (3)What is the function of the high voltage across the X-ray tube? 2 × 3to accelerate/ pull / attract /give more energy to // to produce 3electrons // cathode rays / X -rays 3Name a suitable material for the target in the X-ray tube 4tungsten, molybdenum 4Give one use of X-rays 6 or 3to photograph bones/ internal organs, to treat cancer, to detect flawsin materials, to determine the thickness of materials, etc. any one 6partial answer e.g. reference to photograph / medicine / industry, etc (3)

2004 HL Q9Distinguish between photoelectric emission and thermionic emission. (12)P.E.E.: emission of electrons // T.I.E.: emission of electrons 3+3light (of suitable frequency) falls on a metal // from (surface of) hot metal 3+3A freshly cleaned piece of zinc metal is placed on the cap of a negatively charged gold leafelectroscope and illuminated with ultraviolet radiation. Explain why the leaves of theelectroscope collapse. (9)photoelectric emission (or effect) occurs / electrons emitted 6leaves become uncharged (and collapse) / repulsion between leaves lessens /p.d. between leaves and chassis decreases 3Explain why the leaves do not collapse when:(i) the zinc is covered by a piece of ordinary glass;(ii) the zinc is illuminated with green light;(iii) the electroscope is charged positively. (15)(i) ordinary glass does not transmit UV light 3(ii) no electrons emitted / photoelectric effect does not occur 3E or f too low / λ too long / work function of metal not overcome 3(iii)(any) electron emitted // no electron emitted 3attracted back to the positive electroscope // charge on leaves is constant 32003 OL Q5(j) (small) mass (9.1 × 10-31 kg), (negative) charge (-1.6 × 10-19 C), orbits the nucleus,outside the nucleus, deflected by electric / magnetic fields etc. any two 7any one (4)2003 OL Q10What is radioactivity? 2 × 3disintegration / decay of nuclei / atoms 3emission of radiation / energy / α / β / γ 3

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decay of unstable nuclei (2 × 3)Give the function of any two of these 2 ×(6 or 3)(fuel rod) source of energy //contain uranium / fissionable material 6partial answer (3)(control rod) absorb neutrons // speed up / slow down / stop reaction 6partial answer (3)(moderator) slows down neutrons //makes neutrons easier to capture //ensures chain reaction continues 6partial answer (3)(heat exchanger) transfers heat / energy // heats water/steam // cools coolant 6partial answer (3)transposed incorrect answers, maximum mark 6

What is nuclear fission? 3 × 3splitting / breaking 3(of large) nucleus / atom 3(with) release of (large amounts of) energy / two nuclei of roughly equal size 3diagram may merit marksWhat is a chain reaction? 3 × 3(at least one) neutron released 3(during) fission (reaction) stated or implied 3causes more fission / absorbed by another nucleus 3self sustaining reaction (3 × 3)repeats continuously // relevant mention of critical mass (2 × 3)diagram may merit marksName three types of radiation that are present in a nuclear reactor 3 × 3alpha / α 3beta / β 3gamma / γ 3Name an instrument used to detect radiation 5 h/mGM tube, solid state detector, cloud chamber, ionisation tube,scintillation counter, gold leaf electroscope etc. any one 5Give two precautions that are taken when storing the plutonium 2 × 3(thick) shielding, long life (containers), security (against theft), isolating,handling / use a tongs, labelling etc. any two 2 × 3

2003 OL Q12(d)What is a photon? 2 × 3bundle / packet 3of energy / light 3E = hf (2 × 3)Name the parts labelled A and B 2 × 3(A is the photo) cathode 3(B is the photo) anode 3reverse order (3)

What happens at A when light falls on it? 2 × 3electrons / charged particles // current 3are released / emitted // flows 3gains energy / galvanometer / meter deflects / turns on (3)What happens in the circuit when the light falling on A gets brighter? 2 × 3

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current / I // meter reading 3increases 3Give an application of a photocell 4 h/malarms, automatic doors, safety switches, light meters, solar cells etc. any one 4

2003 HL Q5

(h) What is the photoelectric effect?emission of electrons (from a metal) 4by light / electromagnetic radiation / photons 3(i) What is meant by nuclear fusion?combining of two (small) nuclei 4release of energy / large nucleus 3

2003 HL Q9

List two properties of the electron. (6)negative charge, mass = 1/1836 amu (approx = 0), orbits nucleus,deflected by electric / magnetic field etc. 2 x 3Name the Irishman who gave the electron its name in the nineteenth century. (6)(G. J.) Stoney 6Give an expression for the force acting on a charge q moving at a velocity v at right angles to a magnetic field of flux density B. (6)qvB 6evB (3)What happens to the energy of the electron when it hits thescreen of the CRT? (5)converted to light / heat / does not hit screen / flourescence 5

2003 HL Q11

(a) What is radioactive decay? (7)breakup of a nucleus 4release of radiation / λ /β /γ 3(b) What is an isotope? (7)same atomic number / same number of protons 4different atomic mass / different number of neutrons 3(c) Apart from “carbon dating”, give two other uses of radioactive isotopes. (7)medical imaging, (battery of) heart pacemakers, sterilization,tracers, irradiation of food, killing cancer cells,measuring thickness, smoke detectors, nuclear fuel 4 + 3(d) How many neutrons are in a 14C nucleus? (7)eight 7(e) 14C decays to 14N. Write an equation to represent this nuclear reaction.(7)

( if atomic numbers are missing award a maximum of 4) (-1 for lack of units or incorrect units)(h) Why does the 12C in dead tissue remain “undisturbed”? (7)It is not radioactive / it is not exchanging with the atmosphere /it is stable 7

2002 OL Q10

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What 3 3releasing/ giving off / emission 3electrons 3(from) hot (surface) 3Name 4 3A filament/heater 3B cathode 3C attracts electrons/ focus/gives beam 3D screen 3B and C reversed maximum 3 3Functions 2 6A heats (the cathode)B source of electronsC attracts electrons/ focus/gives beamD (fluorescent screen) detects electrons // converts Ek to lightany two 2 6Deflected 6 h/melectric field/electrode/magnetic field/magnet/X-Y plates 6Use 3TV/ X-ray machine/oscilloscope/ computer monitor /heart monitor/ECG/ brainmonitor/EEG/etc any one 3Sketch 3 3 + 2heater, cathode, anode, target, high voltage any three 3 3correct arrangement for any three of the above 2Why 3protection/safety 3

2002 OL Q11(a) release/leakage 4of radiation/radioactive materials/energy (due to a mishap/fire/explosion) 3(b) splitting of a nucleus/atom (into two parts) 7reference to splitting, /releasing energy/neutrons//radiation (4)(c) coolant, fuel rods, control rods, shielding, moderator, coreany two 7one correct (4)(d) rate of decay /activity (of a radioactive substance) ) 7reference to number of emissions (4)(e) iodine, caesium, radon, carbon 14, etc. any two 7one correct (4)(f) time it takes 4(for ) half the radioactive nuclei/atoms/substance to decay // activity to halve 3(g) (radiation which is) in the environment/atmosphere/air/always there/due torocks/cosmic/natural (radiation) 7partial answer (4)

(h) cancer, skin burns, sickness, kills cells genetic effects, death, cures cancerouseffects, sterilise, etc. any one 4any other 3

2002 HL Q5

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(j) splitting (large) nucleus 4release of energy / radiation / nuclei / neutrons 3

2002 HL Q9Production of X-rayshot cathode / filament 3labelled target 3indication of high voltage 3vacuum / shield / cooling / window Any two, 2 3

X-ray inverse of photoelectricX-ray PhotoelectricElectrons / cathode rays in electrons outradiation / light out radiation / light in 6 + 3

Demonstrate photoelectric effect.suitable light // shine light 3metal plate / cap // photocell 3(negatively charged) electroscope // milliammeter 3leaves fall // current 3

Einstein’s explanation.photon / energy packet / quantum 3E hf 3gives (all) energy to electron 3work function / threshold frequency or wavelength 3rest as kinetic energy of electron / electrons released 3(final 4 x 3 may be obtained by writing Einstein’s photoelectric equation)

Applications of photocellburglar alarmsmoke alarmssafety switchlight metersautomatic lightscountersautomatic doorscontrol of central heating burnerssound track in filmsscannerreading bar codesstopping conveyer belt 3 + 2

2002 Q12(d)Name the scientistRutherford / Geiger / Marsden 4What was observedmost alphas passed straight through 6some deflected / scattered through large angles 3Why in vacuumto prevent alphas colliding with other particles (and

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being scattered) / range of alphas in air is (very) short 6(any reference to collisions 3)Conclusionnucleus / small dense core 6positive / surrounded by empty space / orbiting electron cloud 3

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6th Year Physics: Particle Physics Theory

2013 Q5(j)

(j) Give an expression for the minimum frequency of a photon that can form an electron and a positron by pair production.

f =2me c2

h(4 marks for hf or mc2) 7

2013 Q10(a)

(a) In 1932 J.D. Cockroft and E.T.S. Walton accelerated protons to energies of up to 700 keV and used them to bombard a lithium target. They observed the production of alpha-particles from the collisions between the accelerated protons and the lithium nuclei. How did Cockroft and Walton accelerate the protons? high voltage / large electric field 6 How did they detect the alpha-particles? scintillations / flashes of light / fluorescence 3 when particles hit (zinc sulfide) screen 3 Write the nuclear equation for the reaction that occurred and indicate the historical significance of their observation. Li+ H → He+ He2

424

11

37 9 (–1 for each incorrect or omitted symbol or number)

1st experimental verification of E = mc2 / first artificial splitting of the nucleus (atom) / first transmutation using artificially accelerated particles / awarded Nobel Prize 3 Many modern particle accelerators, such as the Large Hadron Collider (LHC) in CERN, have a circular design. The diagram shows a simplified design of a circular accelerator. Why is the tube evacuated? so that particles do not collide with gas particles // to increase mean free path 3 What is the purpose of accelerating the particles to high velocities? to overcome repulsive forces // to create new matter 4 What is the purpose of the magnets? to contain the particles (in a circular path) (stated or implied) 4 Give an advantage of a circular accelerator over a linear accelerator. takes up less space // particles can achieve greater energy / speed 3 Can an accelerator of this design be used to accelerate neutrons? Explain your answer. no 3 neutrons have no charge and are therefore not affected by electric / magnetic fields 3

2012 HL Q5(j)

(j) Which Irish physicist is associated with the development of the linear accelerator?Walton

7

2012 HL Q10(a)(a) (i) What is a positron?

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an electron with + charge / electron antiparticle / 6

(ii) When a positron and an electron meet two photons are produced.Write an equation to represent this interaction

(iii) Why are photons produced in this interaction?mass converted into energy

3Explain why two photons are produced.to conserve momentum

3Explain why the photons produced usually have a greater f than your calculated minimum f value.(in addition to rest mass) the colliding particles have kinetic energy

3

(iv) Why must two positrons travel at high speeds so as to collide with each other?to overcome force of repulsion

6How are charged particles given high speeds?particle accelerators / linear accelerator / cyclotron /synchrotron/magnetic fields/electric fields 6

(v) Explain why two positrons cannot annihilate each other in a collision.(in conflict with) conservation of charge or equivalent statement

8(‘zero charge after interaction’ …. award 4 marks)

2011 HL Q5

(j) Give the difference between the quark composition of a baryon and of a meson.Baryon: 3 quarks

Meson: quark and antiquark 4+3

2011 HL Q10

(a) List three quantities that are conserved in nuclear reactions.momentum, charge, mass-energy, nucleons, etc. (any three valid answers)

2+2+2Write an equation for a nucleus undergoing beta-decay.

3×3In initial observations of beta-decay, not all three quantities appear to be conserved.What was the solution to this contradiction?

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proposal/discovery of the neutrino/ υ 3

List the fundamental forces of nature in increasing order of their strength.gravitational < weak (nuclear) < electromagnetic < (strong) nuclear

3×3(3 marks for naming any two; 2×3 marks for naming the correct four; 3 marks for correct order)Which fundamental force of nature is involved in beta-decay?weak (nuclear)

3In the Large Hadron Collider, two protons with the same energy and travelling in opposite directions collide. Two protons and two charged pi mesons are produced in the collision. Why are new particles produced in the collision?energy is converted into mass / E = mc2

3Write an equation to represent the collision.

3×3(3 marks for showing 2 p before and after; 3 marks for showing two pions ; 3 marks for correct format)

2010 HL Q5

(j) Give two advantages of a circular accelerator over a linear accelerator.smaller (less space) // greater speeds/energy // etc. any two 4 + 3

2010 HL Q10

(a)(i) What is anti-matter?material/matter/particle that has same mass as another particle 3(but equal in magnitude and) opposite charge 3An anti-matter particle was first discovered during the study of cosmic rays in 1932.Name the anti-particle and give its symbol.positron / anti-electron 3e/ / e 3What happens when a particle meets its anti-particle?(entire) mass converted to / pair annihilation occurs (followed by creation of) 3energy / photon(s) 3(ii) What is meant by pair production?particle and (its) antiparticle created 3from energy / gamma rays 3(the production of a positron and an electron from a gamma ray photon … 6 marks )

2009 HL Q5(j) Arrange the fundamental forces of nature in increasing order of strength.

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name the four forces 4×1in correct order (gravitational, weak, electromagnetic, strong) 3( –1 if order reversed)

2009 HL Q10(a)In 1932 Cockcroft and Walton succeeded in splitting lithium nuclei by bombardingthem with artificially accelerated protons using a linear accelerator. Each time alithium nucleus was split a pair of alpha particles was produced.How were the protons accelerated? How were the alpha particles detected?high voltage 4scintillations / flashes of light / zinc sulphide (or phosphor) screen 4Write a nuclear equation to represent the splitting of a lithium nucleus by a proton.

Most of the accelerated protons did not split a lithium nucleus. Explain why.atom mostly empty space 3protons did not collide with lithium nucleus / passed straight through 3Cockcroft and Walton’s apparatus is now displayed at CERN in Switzerland, wherevery high energy protons are used in the Large Hadron Collider. In the Large HadronCollider, two beams of protons are accelerated to high energies in a circular accelerator. The two beams of protons then collide producing new particles. Each proton in the beams has a kinetic energy of 2.0 GeV.Explain why new particles are formed.kinetic energy of protons // energy converted 3changed into mass // into mass 3[ e.g. ‘mass/energy conservation’ ... 2 × 3]What is the advantage of using circular particle accelerators in particle physics?take up less space // greater (particle) speeds / energy 6

2008 HL Q5(j) The existence of the neutrino was proposed in 1930 but it was not detected until 1956. Give

two reasons why it is difficult to detect a neutrino. uncharged /very small (mass) /zero mass / interact weakly with matter (any two) 4+3

2008 HL Q10 (a)(a) Baryons and mesons are made up of quarks and experience the four fundamental forces of nature. List the four fundamental forces and state the range of each one.

Name the three positively charged quarks. up, top, charm / u, t, c 2+2+2

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What is the difference in the quark composition of a baryon and a meson? (baryon): three quarks 3

(meson): one quark and one antiquark 3 What is the quark composition of the proton?

up, up, down ( –1 per incorrect item) 3 In a circular accelerator, two protons, each with a kinetic energy of 1 GeV, travelling in opposite directions, collide. After the collision two protons and three pions are emitted. What is the net charge of the three pions? Justify your answer.

zero 6 (electric) charge is conserved 3

2007 HL Q5(j) A kaon consists of a strange quark and an up anti-quark. What type of hadron is a kaon?a meson 7

2007 HL Q10(a)(i) Draw a labelled diagram to show how Cockcroft and Walton accelerated the protons.anode and cathode (in tube) / (lithium) target / two helium nuclei 3p.d / V / H.T 3Write a nuclear equation to represent the disintegration of a lithium nucleus when bombarded with a proton.

(accept p for H and α for He ; -1 for each error) 3 x 3

(ii) Compare the properties of an electron with that of a positron.(both have) equal mass / charges equal / charges opposite (in sign) / matter and anti-matterany one direct comparison 5What happens when an electron meets a positron?(pair) annihilation / energy released(or produced) / γ -rays emitted 3

(iii) In beta decay it appeared that momentum was not conserved.How did Fermi’s theory of radioactive decay resolve this?any reference to neutrino 6(neutrino had the missing) momentum 3

2006 HL Q5

(j) Name the three negatively charged leptons.

Name: electron (e) , muon (μ), tau (τ ) 3+2+2

2006 HL Q10(a)(a) During a nuclear interaction an antiproton collides with a proton. Pair annihilation takes place and two gamma ray photons of the same frequency are produced. What is a photon? packet /bundle /quantum of (electromagnetic or light ) energy /radiation 3

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Why are two photons produced? Describe the motion of the photons after the interaction. (9) so that momentum is conserved / so that momt. before = momt. after 6 they travel in opposite directions 3 How is charge conserved during this interaction? (6) (total) charge before = +1-1 = 0 3 (total) charge after = 0 since photons have zero charge 3 After the annihilation, pairs of negative and positive pions are produced. Explain why. (6) energy (of photons) is converted into matter / pair production occurs / to conserve charge 6 Pions are mesons that consist of up and down quarks and their antiquarks. Give the quark composition of (i) a positive pion, (ii) a negative pion. (9) any quark , antiquark pair 3 π+ => up and anti-down / ud 3 π- => down and anti-up / d u 3 List the fundamental forces of nature that pions experience. (6) electromagnetic, strong (nuclear), weak (nuclear), gravitational (any order) 2+2+1+1

2005 HL Q5(j) Name the fundamental force of nature that holds the nucleus together. (7)strong 4 nuclear 3

2005 HL Q11(a)(i) What is the structure of an alpha particle? (7) Two protons // helium 4 two neutrons // nucleus (in context) 3 (ii) Rutherford had bombarded gold foil with alpha particles. What conclusion did he form about the structure of the atom? (7) (dense) positive core / nucleus 4 (atom) mostly empty space / radius of nucleus ≈ 10-15 m / radius of atom ≈ 10-10 m 3 (iii) High voltages can be used to accelerate alpha particles and protons but not neutrons. Explain why. (7) alpha particles and protons are charged 4 neutrons are not charged 3 (iv) Cockcroft and Walton, under the guidance of Rutherford, used a linear particle accelerator to artificially split a lithium nucleus by bombarding it with high-speed protons. Copy and complete the following nuclear equation for this reaction. (7)

(v) Circular particle accelerators were later developed. Give an advantage of circular accelerators over linear accelerators. (7)

(progressively) increasing (or more) energy/speed attainable / more compact / occupy less space any one 7 (vi) In an accelerator, two high-speed protons collide and a series of new particles are produced, in addition to the two original protons. Explain why new particles are produced. (7)

(kinetic) energy (of the protons) 4

converted into mass (of new particles) 3

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(vii) A huge collection of new particles was produced using circular accelerators. The quark model was proposed to put order on the new particles. List the six flavours of quark. (7)

Up, down, charm, strange, top, bottom (6 × 1) + 1 (viii) Give the quark composition of the proton. (7) Up, up, down h/m 7

2004 HL Q5(j) Give the quark composition of the neutron. (7)reference to three quarks (4)up, down, down ( udd) 7

2004 HL Q10(a)Beta decay is associated with the weak nuclear force. List two other fundamental forces ofnature and give one property of each force. (12)strong (nuclear) force /gravitational force /electromagnetic force any two: 3 + 3strong: acts on nucleus/protons + neutrons/hadrons/baryons/mesons, short rangegravitational: attractive force, inverse square law/infinite range, all particleselectromagnetic: acts on charged particles, inverse square law/infinite rangeone property of each of the two other fundamental forces listed: 3 + 3In beta decay, a neutron decays into a proton with the emission of an electron. Write anuclear equation for this decay.

Momentum and energy do not appear to be conserved in beta decay. Explain how theexistence of the neutrino, which was first named by Enrico Fermi, resolved this. (8)“missing” momentum provided by the neutrino 4“missing” energy provided by the neutrino 4(“momentum and energy are conserved when the momentum and energy of the (associated)neutrino are taken into account”. 4 + 4)During the late 1930’s Fermi continued to work on the nucleus. His work led to the creationof the first nuclear fission reactor in Chicago during 1942. The reactor consisted of a ‘pile’of graphite moderator, uranium fuel with cadmium control rods. (15)(i) What is nuclear fission?splitting of a large nucleus 3into two similar-sized/smaller nuclei + energy ( -1 per missing item) 3( –1 if atom used instead of nucleus)(ii) What is the function of the moderator in the reactor?slows down fast neutrons ( -1 if fast omitted) 6(iii) How did the cadmium rods control the rate of fission?(they) absorbed neutrons 3

2003 HL Q5(j) Give one contribution made to Physics by either Paul Dirac or Nicholas Callan. (7)

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Dirac; (predicted ) positrons / antiparticles / antimatteroperator theory / quantum algebraCallan: induction coil / batteries / prevent rusting any one 7

2003 HL Q10(a)Leptons, baryons and mesons belong to the “particle zoo”.Give (i) an example, (ii) a property, of each of these particles. (18)LEPTONS; electron / positron / muon / tau / neutrino 3not subject to strong force / any individual property 3BARYONS; proton / neutron 3subject to all forces / three quarks / any individual property 3MESONS pi(on) / kaon 3subject to all forces / mass between electron and protonquark and antiquark / any correct charge 3What is the effect on the products of the reaction if the frequency of the γ-ray photonexceeds the minimum value? (5)kinetic energy / speed / moving / more particles 5

The reverse of the above reaction is known as pair annihilation. Write a reaction thatrepresents pair annihilation. (6)

6 (-3 per missing item)Explain how the principle of conservation of charge and the principle of conservationof momentum apply in pair annihilation. (12)total charge on both sides is zero 6electron and positron have opposite charges (3)photons in opposite directions /momentum of positron + electron = momentum of photons 6momentum before = momentum after = zero (3)

2002 HL Q10(a)

Four fundamental forcesgravitational 3electromagnetic 3strong (nuclear) 3weak (nuclear) 3Name of force for binding nucleusstrong 3Two properties of forceshort range, strong(est),act on nucleons, binds nucleus Any two 2 x 3Outline of Cockroft and Waltonmoving protons 3high voltage 3alpha particles released 3screen / microscope 2Nuclear equation

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