9702 w04 ms_all

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary/Advanced Level

MARK SCHEME for the November 2004 question paper

9702 Physics

9702/01 Paper 1 (Multiple Choice), maximum raw mark 40

Mark schemes must be read in conjunction with the question papers and the Report on the

Examination.

• CIE will not enter into discussion or correspondence in connection with these mark schemes.

CIE is publishing the mark schemes for the November 2004 question papers for most IGCSE and GCE Advanced Level syllabuses.

Grade thresholds taken for Syllabus 9701 (Physics) in the November 2004 examination.

minimum mark required for grade: maximum mark

available A B E

Component 1 40 33 30 23

The thresholds (minimum marks) for Grades C and D are normally set by dividing the mark range between the B and the E thresholds into three. For example, if the difference between the B and the E threshold is 24 marks, the C threshold is set 8 marks below the B threshold and the D threshold is set another 8 marks down. If dividing the interval by three results in a fraction of a mark, then the threshold is normally rounded down.

November 2004

GCE AS/A LEVEL

MARK SCHEME

MAXIMUM MARK: 40

SYLLABUS/COMPONENT: 9702/01

PHYSICS Paper 1

(Multiple Choice)

Mark Scheme Syllabus Paper

GCE AS/A LEVEL – NOVEMBER 2004 9702 1

© University of Cambridge International Examinations 2005

Question Number

Key Question Number

Key

1 C 21 A

2 C 22 A

3 D 23 A

4 A 24 D

5 B 25 C

6 D 26 C

7 D 27 C

8 C 28 D

9 D 29 A

10 B 30 D

11 B 31 C

12 C 32 B

13 B 33 C

14 B 34 C

15 A 35 D

16 A 36 B

17 B 37 A

18 A 38 D

19 B 39 C

20 A 40 D


GCE Advanced Subsidiary and Advanced Level


9702 PHYSICS

9702/02 Paper 2 (Structured), maximum raw mark 60

This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. This shows the basis on which Examiners were initially instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began. Any substantial changes to the mark scheme that arose from these discussions will be recorded in the published Report on the Examination. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes must be read in conjunction with the question papers and the Report on the Examination.

• CIE will not enter into discussion or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the November 2004 question papers for most IGCSE and GCE Advanced Level syllabuses.



available A B E

Component 2 60 41 37 25


November 2004

GCE A AND AS LEVEL

MARK SCHEME

MAXIMUM MARK: 60


PHYSICS Paper 2 (Structured)


A and AS LEVEL – NOVEMBER 2004 9702 2


1 (a) (i) e.g. check for zero error (on micrometer)/zero the micrometer B1 (ii) take readings along the length of the wire/at different points B1 (iii) take readings spirally/around the wire B1 [3] (b) (i) 4% A1 (ii) 8% A1 [2] 2 (a) all same speed in a vacuum (allow medium)/all travel in a vacuum (1) transverse/can be polarised (1) undergo diffraction/interference/superposition (1) can be reflected/refracted (1) show properties of particles (1) oscillating electric and magnetic fields (1) transfer energy/progressive (1) not affected by electric and magnetic fields (1) (allow any three, 1 each) B3 [3] (b) 495 nm = 495 x 10-9 m C1 number = 1/(495 x 10-9) = 2.02 x 106 A1 [2] (allow 2 or more significant figures) (c) (i) allow 10-7 → 10-11 m B1 (ii) allow 10-3 → 10-6 m B1 [2] 3 (a) constant gradient/straight line B1 [1]

(b) (i) 1.2 s A1

(ii) 4.4 s A1 [2]

(c) either use of area under line or h = average speed x time C1 h = ½ x (4.4 – 1.2) x 32 C1 = 51.2 m A1 [3] (allow 2/3 marks for determination of h = 44 m or h =58.4 m allow 1/3 marks for answer 7.2 m)




(d) ∆p = m∆v OR p = mv C1 = 0.25 x (28 + 12) C1 = 10 N s A1 [3] (answer 4 N s scores 2/3 marks)

3 (e) (i) total/sum momentum before = total/sum momentum after B1 in any closed system B1 [2] (ii) either the system is the ball and Earth B1 momentum of Earth changes by same amount B1 but in the opposite direction B1 or Ball is not an isolated system/there is a force on the ball (B1) Gravitational force acts on the ball (B1) causes change in momentum/law does not apply here (B1) [3] (if explains in terms of air resistance, allow first mark only) 4 (a) wavelength = 1.50 m B1 [1]

(b) v = f λ C1

speed = 540 m s-1 A1 [2]

(c) (progressive) wave reflected at the (fixed) ends B1 wave is formed by superposition of (two travelling) waves B1 this quantity is the speed of the travelling wave B1 [3]

5 (a) (i) F/A B1

(ii) ∆L/L B1 (iii) FL/A.∆L B1 [3] (b) (i) ∆L = 0.012 x 0.62 x 350 M2 = 2.6 mm A0 [2] (ii) 2.0 x 1011 = (F x 0.62)/(7.9 x 10-7 x 2.6 x 10-3) C1 F = 660 N A1 [2]




(iii) either stress when cold = 660/(7.9 x 10-7) = 840 MPa or tension at uts = 198 N M1 either this is greater than the ultimate tensile stress or tension at uts is less then tension in (ii) A1 the wire will snap A1 [3] (Allow possibility for the two ‘A’ marks to be scored as long as some quantitative

answer – even if incorrect – has been given for the ‘M’ mark)

6 (a) (i) resistance is ratio V/I (at a point) B1 either gradient increases or I increases more rapidly than V B1 [2] (If states R = reciprocal of gradient, then 0/2 marks here) (ii) current = 2.00 mA C1 resistance = 2 000 Ω A1 [2]

(b) (i) straight line from origin M1

passing through (6.0 V, 4.0 mA) (allow ½ square tolerance) A1 [2] (ii) individual currents are 0.75 mA and 1/33 mA C1 current in battery = 2.1 mA A1 [2] (allow argument in terms of P = I2R or IV)

(c) same current in R and in C M1 p.d. across C is larger than that across R M1 so since power = VI, greater in C A1 [3]

(allow argument in terms of P = I2R or IV)

7 (a) (i) nucleus is small M1 in comparison to size of atom A1 [2] (ii) nucleus is massive/heavy/dense B1 and charged (allow to be scored in (i) or (ii)) B1 [2] (b) (i) symmetrical path and deviation correct w.r.t. position of nucleus B1 deviation less than in path AB B1 (ii) deviation > 90o and in correct direction B1 [3]




9702 PHYSICS

9702/03 Paper 3 (Practical Test), maximum raw mark 25





available A B E

Component 3 25 22 20 14


November 2004

GCE A AND AS LEVEL

MARK SCHEME

MAXIMUM MARK: 25


PHYSICS Paper 3 (Practical Test)




1 (b) Uncertainty = 1 mm (i.e. 0.5 mm at each end) 1 Percentage uncertainty in first value of d 1 (i.e. ratio correct and x 100) If working not clear (e.g. bald 0.4% to 0.5%), then 1/2 in this section

(c) (ii) Repeated readings in first set of measurements There must be at least two values of t. 1

(d) Readings 3 Expect to see 6 sets of raw readings (1 mark).

Write the number of readings as a ringed total by the table. Check a value for T 2. Underline checked value and tick if correct (1 mark). If the number of oscillations has not been recorded, do not award this mark. If T 2 incorrect, write in correct value. Ignore small rounding errors. Check a value for d 3. Underline this value and tick if correct (1 mark). If incorrect, write in correct value. Ignore small rounding errors. Minor help given by Supervisor, then -1. Excessive help then -2.

Reasonable time used for oscillations 1 At least half of the raw times must be greater than 20 s. Quality of results 1 Judge by scatter of points about the line of best fit. This mark may be scored for 5 trend plots with small scatter. Wrong trend/curved trend will not score this mark.

This mark can only be scored if the plotted points occupy more than 2 large squares in the y-direction.

Column headings 2 Apply to T 2 and d 3 only. One mark each. The headings must contain a quantity and a unit Consistency in raw values 2 Apply to t and d only. One mark each

All the values of t should be given to the nearest 0.01 s or 0.1 s. All the values of d must be given to the nearest millimetre.

Significant figures 2 Apply to T 2 and d 3 only. One mark each.

All the values of T 2 must be given to 3 or 4 s.f. If d given to 1 s.f., then accept d 3 to 1 or 2 s.f. If d given to 2 s.f., then accept d 3 to 2 or 3 s.f. If d given to 3 s.f., then accept d 3 to 3 or 4 s.f. Check each value by row in the table.




(e) Axes 1 Scales must be such that the plotted points occupy at least half the graph grid in both the x and y directions. Scales must be labelled with the quantity plotted. Ignore units. Do not allow awkward scales (e.g. 3:10, 6:10, 7:10 8:10 etc.). There must be no more than 3 large squares without a scale marking.

Plotting of points 1 Write the number of plots as a ringed total on the graph grid. All observations must be plotted. Check a suspect plot. Circle and tick if correct. If incorrect, show correct position with arrow, and -1. Work to half a small square.

Line of best fit 1 There must be a reasonable balance of points about the line of best fit. Allow one ‘off trend’ plot to be ignored. Only allow a straight line through a linear trend.

Determination of gradient 1 ∆ used must be greater than half the length of the drawn line. ∆x/∆y scores zero. Check the read-offs. Do not allow tangents to curves.

y-intercept 1 The value may be read directly or calculated using y = mx + c and a point on the line. Work to half a small square.

(f) Gradient equated with k 1

Do not award this mark if wrong graph (e.g. T vs d, d 3 vs T 2 etc.) Value of k with unit (e.g. s2 m-3 or s2 cm-3) 1

Unit must be consistent with value. Any POT error will not score this mark.

Intercept equated with g

l42

π

1

Value of g with unit (e.g. m s-2 or cm s-2) 1

This mark is conditional on the previous mark being scored. Unit must be consistent with value. Value should be 19.7/y-intercept. Method of working must be correct.

Simultaneous equation method can score 1 mark if the units of k and g are correct.




(g) (i) Calculation of d when T = 2 s 1 Method of working must be correct. A final numerical answer is expected

(ii) d too large for case (approx 45 cm width). 1

Accept sensible answers consistent with candidate's result from (g) (i). Be generous. Accept values to 0.50 m as small. Some justification needed.

25 marks in total


GCE Advanced Level


9702 PHYSICS

9702/04 Paper 4 (Core), maximum raw mark 60





available A B E

Component 4 60 39 34 18


November 2004

GCE A LEVEL

MARK SCHEME

MAXIMUM MARK: 60


PHYSICS Paper 4 (Core)


A LEVEL – NOVEMBER 2004 9702 4


1 (a) θ (rad) = 2π x (10.3/360) 1

= 0.180 rad (n.b. 3 sig. fig.) 1 [2] (b) (i) tan θ = 0.182 (n.b. 3 sig. fig.) 1 (ii) percentage error = (0.002/0.180) x 100 1 = 1.1 (%) 1 [3] (allow 0.002/0.182 and allow 1 4 sig. fig.) 2 (a) (i) grav. pot. energy = GM1M2/R 1 energy = 6.67 x 10-11 x 197 x 4 x (1.66 x 10-27)2/9.6 x 10-15 1 = 1.51 x 10-47 J 1 [3]

(ii) elec. pot. energy = Q1Q2/4π ε 0R 1

energy = 79 x 2 x (1.6 x 10-19)2/4π x 8.85 x 10-12 x 9.6 x 10-15 1 = 3.79 x 10-12 J 1 [3] (For the substitution, -1 each error or omission to max 2 in (i) and in (ii)) (b) electric potential energy >> gravitational potential energy 1 [1] (c) either 6 MeV = 9.6 x 10-13 J or 3.79 x 10-12 J = 24 MeV 1 not enough energy to get close to the nucleus 1 [2] 3 (a) (i) reasonable shape as ‘inverse’ of k.e. line 1 (ii) straight line, parallel to x-axis at 15 mJ 1 [2] (b) either (max) kinetic energy (= ½ mv2) = ½ mω

2a0

2 1

15 x 10-3 = ½ x 0.15 x ω 2 x (5.0 x 10-2)2 1

ω = 8.9(4) rad s-1 1

or (k.e. = ½ mv2), v = 0.44(7) m s-1 1 ω = v/a = (0.447)/(5.0 x 10-2) 1

ω = 8.9(4) rad s-1 1 [3]

(c) (i) either loss of energy (from the system) or amplitude decreases

or additional force acting (on the mass) 1 either continuous/gradual loss or force always opposing motion 1 [2] (ii) either (now has 80% of its) p.e./k.e. = 12 mJ or loss in k.e. = 3 mJ 1 new amplitude = 4.5 cm (allow ± 0.1 cm) 1 [2]




4 (a) (i) 50 mT 1 (ii) flux linkage = BAN 1 = 50 x 10-3 x 0.4 x 10-4 x 150 = 3.0 x 10-4 Wb 1 [3] (allow 49 mT 2.94 x 10-4 Wb or 51 mT 3.06 x 10-4 Wb) (b) e.m.f./induced voltage (do not allow current) proportional/equal to 1 rate of change/cutting of flux (linkage) 1 [2] (c) (i) new flux linkage = 8.0 x 10-3 x 0.4 x 10-4 x 150 = 4.8 x 10-5 Wb 1 change = 2.52 x 10-4 Wb 1 [2] (ii) e.m.f. = (2.52 x 10-4)/0.30 1 = 8.4 x 10-4 V 1 [2] (d) either for a small change in distance x 1 (change in) flux linkage decreases as distance increases 1

so speed must increase to keep rate of change constant 1 [3] or (change in) flux linkage decreases as distance increases (1) at constant speed, e.m.f/flux linkage decreases as x increases (1) so increase speed to keep rate constant (1) 5 (a) into (plane of) paper/downwards 1 [1] (b) (i) the centripetal force = mv2/r 1 mv2lr = Bqv hence q/m = v/r B (some algebra essential) 1 [2] (ii) q/m = (8.2 x 106)/(23 x 10-2 x 0.74) 1 = 4.82 x 107 C kg-1 1 [2] (c) (i) mass = (1.6 x 10-19)/(4.82 x 107 x 1.66 x 10-27) 1 = 2u 1 [2] (ii) proton + neutron 1 [1]

6 (a) (i) either probability of decay or dN/dt = (-)λN OR A = (-)λN 1 per unit time with symbols explained 1 [2] (ii) greater energy of α particle means 0

(parent) nucleus less stable 1 nucleus more likely to decay 1 hence Radium-224 1 [3]

(b) (i) either λ = In2/3.6 or λ = In2/3.6 x 24 x 3 600 = 0.193 = 2.23 x 10-6 1 unit day -1 s-1 1 [2]

(one sig.fig., -1, allow λ in hr-1)




(ii) N = (2.24 x 10-3)/224 x 6.02 x 1023 1 = 6.02 x 1018 1

activity = λN = 2.23 x 10-6 x 6.02 x 1018 1 = 1.3 x 1013 Bq 1 [4] (c) A = A0 e

-ln2.tlT 0.1 = exp(-In2 . n) 1 n = 3.32 1 [2] (n = 3 without working scores 1 mark) 7 (a) variation is non-linear 1 two possible temperatures 1 [2]

(b) e.g. 1. small thermal capacity/measure ∆θ of small object /short response time 2 readings taken at a point/physically small 3 can be used to measure temperature difference 4 no power supply required etc. (any two, 1 mark each) 2 [2]


GCE Advanced Level


9702 PHYSICS

9702/05 Paper 5 (Practical Test), maximum raw mark 30





available A B E

Component 5 30 24 22 15


November 2004

GCE A LEVEL

MARK SCHEME

MAXIMUM MARK: 30


PHYSICS Paper 5 (Practical Test)




1 (b) (iii) Explanation of positioning of magnet 1 (e.g. place eye level with top of coil/measure length of magnet outside coil) (d) Readings 3

6 sets then 3; 5 sets then 2; 4 sets then 1; 3 sets or less scores zero Allow more than 6 sets without penalty. Allow current values to be greater than 5 A. Allow I = 0 to be one of the values in the table. Any POT error then -1. Write the number of readings as a ringed total by the table. Minor help from the Supervisor, 1. Major help, then -2. If help has been given then write SR at the top of the front page of the script, and give a brief explanation of the type of help that has been given by the table of results.

Repeated readings 1

There must be at least two sets of readings for either F or I. Allow all the readings to be identical.

Column headings 1

Each column heading must contain a quantity and a unit. There must be some distinguishing feature between the quantity and the unit.

Consistency of raw readings 1 All the raw readings of F should be given to the same number of d.p. All the raw readings of I should be given to the same number of d.p. Expect to see values to one or two d.p. only. Clearly manufactured readings scores zero.




Graph Axes 1

The axes must be labelled with the quantities plotted. Ignore units on the axes. The plotted points must occupy at least half the graph grid in both the x and y directions (i.e. 4 large squares in the x-direction and 6 large squares in the y-direction). Do not allow more than 3 large squares between the labels on an axis. Do not allow awkward scales (e.g. 3:10, 6:10 etc.).

Graph Plotting of points 1

All the observations must be plotted. Count the number of plots and ring this total on the grid. Do not allow plots in the margin area. Check one suspect plot. Circle this plot. Tick if correct. If incorrect, mark the correct position with a small cross and use an arrow to indicate where the plot should have been, and -1. Allow errors up to and including half a small square. Only a drawn straight line through a linear trend is allowable for this mark. This mark can only be awarded for 5 or more plots on the grid. There must be a reasonable balance of points about the drawn line. Do not allow a line of thickness greater than half a small square.

Graph Line of best fit 1 Only a drawn straight line through a linear trend is allowable for this mark This mark can only be awarded for 5 or more plots on the grid. There must be a reasonable balance of points about the drawn line. Do not allow a line of thickness greater than half a small square. Graph Quality of results 1

Judge by scatter of points about the line of best fit. Accept five good trend plots. Poor trend/no trend/wrong trend scores zero.




(e) (iii) Gradient 1

Ignore any units given with the value. Hypotenuse of ∆ must be > half the length of line drawn. Check the read-offs. Work to half a small square. A∆/A∆ gets zero. Values taken from the table that lie on the line to within half a small square are acceptable.

y-intercept 1

(f) k = gradient, W = y-intercept 1 Graph of I vs F will not score this mark unless analysis is consistent. Unit of k and unit of W (i.e. N A-1 and N respectively) 1 SF in k 1 Allow 2 of 3 sf only

(g) Deducting the weight of the magnet from F will give a straight line passing through the origin and therefore force of attraction is proportional to current. 2

If the weight of the magnet is not taken into consideration, then score zero. Statement that force of attraction is not directly proportional to current scores zero. (h) (i) Value of l when F = 10 N 1

Working must be checked. (ii) Overheating problems with the coil when F = 10 N 1 Do not allow answers such as ‘large voltage cannot be obtained from the psu’ 20 marks in total Question 2 A1 Procedure OK (i.e. measure P and f; change P and repeat). 1

This mark can be scored even if the method is unworkable.

A2 Diagram of workable arrangement 2

Source of sound + pump (1 mark); microphone + CRO (1 mark)

Allow ½ if all apparatus is inside the bell jar.

Allow ½ if the container is open.




A3 Measurement of P 1

(e.g. Bourdon gauge/pressure gauge/manometer/barometer). Must be shown correctly on the diagram.

B1 Correct measurements taken to find frequency using CRO 1

Length of trace on screen + timebase setting

B2 Use of measurements to calculate frequency, or f = 1/T 1

B3 Maintain constant temperature whilst pressure is reduced 1 OR maintain constant frequency as pressure is reduced

OR close tap before taking readings C Safety precaution 1 Safety screens/goggles D1/2 Any further good design features 2

Some of these might be: Difficulty with detecting sounds of low intensity at low pressures Use a signal generator connected to speaker Vacuum grease the wires to the speaker Allow time between readings for apparatus to warm up/cool down Monitor temperature with thermometer during experiment Avoid unwanted sounds/use soundproof room Source of sound and microphone both inside the chamber Increase P as well as decrease P to give wide spread of readings 10 marks in total




Summary of shorthand notation which may be used in annotating scripts:

SFP Significant figure penalty

ECF Error carried forward

AE Arithmetical error

POT Power of ten error

NV Not valid

NR Not relevant

NBL Not best line

FO False Origin

NGE Not good enough

BOD Benefit of the doubt

NA Not allowed

SV Supervisor’s value

SR Supervisor’s report

OOR Candidate’s value is out of range

CON Contradictory physics not to be credited

∆ Used to show that the size of a triangle is appropriate (gradient calculation)

C Used to show that the raw readings are consistent

SF Used to show calculated quantities have been given to an appropriate number of significant figures

^ Piece of work missing (one mark penalty)

^^ Several pieces of work missing (more than one mark penalty)

↔ Scale can be doubled in the x-direction

Scale can be doubled in the y-direction




9702 PHYSICS

9702/06 Paper 6, maximum mark 40

This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. This shows the basis on which Examiners were initially instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began. Any substantial changes to the mark scheme that arose from these discussions will be recorded in the published Report on the Examination. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes must be read in conjunction with the question papers and the Report on the

Examination.




available A B E

Component 6 40 30 27 15


November 2004

GCE A AND AS LEVEL

MARK SCHEME

MAXIMUM MARK: 40


PHYSICS Paper 6




Option A – Astrophysics and Cosmology 1 diameter of the Sun B1 nearest (neighbour) star/Proxima Centauri B1 diameter of (Milky Way) galaxy B1 extent of (visible) Universe (allow diameter/radius) B1 [4] 2 e.g. Atmospheric absorption/scattering M1 means light is too faint Al Light pollution M1 means light cannot be distinguished against background Al [4] Irregular atmospheric refraction/thermal currents (M1) means small objects blurred/not seen (Al) (any two sensible suggestions M1 x 2 plus some further detail of each A1 x 2) 3 (a)(i) either density such that Universe will not collapse or expand indefinitely B1

greater density than ρ0 means collapse (OR vice versa) B1 or determines whether Universe is ‘open’ or ‘closed’ (B1)

greater density than ρ0 means ‘closed’

OR smaller density than ρ0 means ‘open’ (B1) [2] (ii) (if Universe is closed eventually all) kinetic energy of galaxies will be converted to

(gravitational) potential energy B1 (gravitational) potential energy involves the gravitational constant G B1 [2] (b) (i)1 (sensible straight line and) one or two points chosen with attempt at antilogs B1

H0 = 100 km s-1 Mpc-1 (allow 80 → 125 km s-1 Mpc-1) A1 1 Mpc = 3.1× 1019 km C1 H0 = 100/(3.1× 1019) = 3.2× 10-18 s-1 Age = 1/H0 = 3.1× 1017 s A1 [4]

(i)2 ρ0 = (3× 10-182) / (8× π× 6.67× 10-11) C1 = 1.86× 10-26 kg m-3 A1 [2] (ii) number density = (1.86× 10-26) / (1.66× 1027) C1

≈ 10 A1 [2]




Option F – The Physics of Fluids 4 (a) M shown near base of stem B1 [1] (b) (i) density = mass/volume C1 volume submerged in liquid of density 1.0 g cm-3 = 165 cm3 C1 volume submerged in liquid of density 1.1 g cm-3 = 150 cm3 C1 change in volume = 15 cm3 A1 (ii) distance (= 15/0.75) = 20 cm A1 [5] 5 (a) arrows longer at centre than edges M1 arrows parallel and correct relative lengths A1 [2] (b) (i) no unique value of (linear) speed B1 [1] (ii)1 volume flow rate doubles A1 (ii)2 new radius = 1.05 r new flow rate = 1.054× 2 C1 = 2.4(3) times greater A1 [3] 6 (a) (fluid) flow/movement B1 that is erratic/has eddies B1 i.e. speed varies continuously (in magnitude and direction) with time B1 [3] (b) (i) for turbulent flow, FD/v2 C1 v = 58 m s-1 A1 [2]




Option M – Medical Physics 7 (a) pulse of ultrasound B1 reflected from boundaries B1 received (at surface) and processed B1 time for pulse to return gives depth of boundary B1 reflected intensity gives information on nature of boundary B1 [5] (b) fraction = e-23× 0.055 C1 = 0.28 A1 [2] (c) fraction = 0.28× 0.35× 0.28 C1 = 0.027 A1 [2] (or 0.35e-23× 0.11 = 0.028) 8 (a) (i) rays from S converge to point behind retina B1 (ii) range of image distances B1 such that image is tolerably in focus B1 [3] (b) for the same size of patch on the retina M1 focused image is further from the retina A1 (so) depth of focus is increased B1 [3] 9 (a) intensity = (0.33× 10-6) / (65× 10-6) C1 = 5.1 (5.08) × 10-3 W m-2 C1 I.L. = 10 lg (5.08× 10-3) / (1.0× 10-12) C1 = 97 dB A1 [4] (b) (long-term exposure) could cause deafness OR (short-term exposure) could cause tinnitus B1 [1]




Option P – Environmental Physics 10 (a) massive nucleus/named appropriate nucleus splits B1 into two approximately equal parts/named components B1 with the release of neutrons and energy B1 [3] (b) moderator: slows down (high speed) neutrons M1 so that further fissions are more likely/will take place A1 control rods absorb neutrons M1 to provide control over the rate of fission A1 [4] 11 (a)(i) water moved from (area of) trough to crest to form wave B1 potential energy = mgh M1

= ½ λ Awρ× g× A

(must be laid out so that substitutions are obvious) M1

= ½ wA2λ ρg A0 [3]

(ii) there are V/ λ wavecrests passing a point per unit time M1

power = ½ wA2λ ρg× V/ λ A1

= ½ wA2ρgV A0 [2]

(b) e.g hazard to shipping, unsightly, upset to shoaling fish etc. (any sensible suggestion) B1 [1] 12 (a) input shown clearly as 1140 W B1 four outputs labeled correctly M1 arrows having approximately correct ratio of widths A1 [3] (b) electrical heating more efficient at transferring energy to water B1 very little thermal energy escapes because plastic is an insulator B1 gas ring much less efficient because of thermal energy losses to the air B1 thermal energy losses due to conduction as kettle is metal B1 [4]




Option T – Telecommunications 13 (a) box for 1 m – 10 cm labeled T B1 (b) box for 10 cm – 1 cm labeled S B1 [2] 14 (a) frequency of carrier wave varies (in synchrony) with information signal B1 constant amplitude OR carrier frequency >> signal frequency B1 change in frequency measures displacement of information signal B1 rate at which carrier frequency varies gives frequency of information signal B1 [4] (b) (i) period = 0.8 μ s C1

frequency = 1.25 MHz A1 (ii) 125 kHz A1 [3] (c) advantage: e.g. better quality/less interference B1 disadvatange: e.g. more transmitters/more expensive B1 [2] (any sensible suggestions, 1 each) 15 (a) (i) sampled every 0.5 ms C1 frequency = 2.0 kHz A1 (ii) at 1.0 V intervals B1 (iii) 4 bits B1 [4] (b) needs sampling time shorter than smallest peak-trough interval B1

any suggestion of about (0.2 ms or about) 5 kHz (allow 5 kHz → 10 kHz) A1 needs voltage interval less than peak-trough height B1

any suggestion at about 0.3 V (allow 0.1 V → 0.4 V) C1 so either 12/0.3 = 40 OR 11/0.3 = 37 OR 10/0.3 = 34 etc. A1 (ignore binary nature of the ADC and the DAC)

9702 w04 ms_all

Education

mark schemes

b threshold

mark range

c threshold

d threshold

maximum raw mark

maximum mark available

grades c