1. 1. MADE BY- SAMIRAN GHOSH CLASS- XI A
2. 2. Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe. In an older and closely related meaning, "science" also refers to a body of knowledge itself, of the type that can be rationally explained and reliably applied. A practitioner of science is known as a scientist.
3. 3. - Investigations in physics generally follow the scientific method -Observations + initial data collection leading to a question, hypothesis formulation and testing, interpret results + revise hypothesis if necessary, state conclusions -Some hypotheses can be tested by making observations. -Others can be tested by building a model and relating it to real-life situations.
4. 4. - A way of describing the physical world - Physics is understanding the behavior and structure of matter - It deals with how and why matter and energy act as they do -Physics comes from the Greek physis meaning nature and the Latin physica meaning natural things - Energy is the conceptual system for explaining how the universe works and accounting for changes in matter - Although energy is not a thing three ideas about energy are important 1. It is changed from one form to another (transformed) by physical events 2. It cannot be created nor destroyed (conservation) 3. When it is transformed some of it usually goes into heat
5. 5. One large question about scientific theories that excites philosophical and scientific attention concerns the possibility of producing a single theory that will encompass the domains of all the sciences. Many thinkers are attracted by the idea of a unified science, or by the view that the sciences form a hierarchy. Chemical reactions themselves involve the forming and breaking of bonds, and these are matters of microphysics. A complete account of those ultimate constituents and their interactions would thus amount to a theory of everything. Reductionism is a philosophical position which holds that a complex system is nothing but the sum of its parts, and that an account of it can be reduced to accounts of individual constituents. This can be said of objects, phenomena, explanation, theories, and meanings.
6. 6. Branch in PHYSICS Thermodynamics Heat and temperature Mechanics Motion and its causes Vibrations and Waves Periodic motion Atomic Structure of the atom, energy associated with atomic changes Nuclear Structure of the nucleus, energy associated with nuclear changes Electromagnetism Electricity, magnetism and EM waves Optics Behavior of light
7. 7. Physics - the study of matter, energy and their interactions - is an international enterprise, which plays a key role in the future progress of humankind. The support of physics education and research in all countries is important because: 1) Physics is an exciting intellectual adventure that inspires young people and expands the frontiers of our knowledge about Nature. 2) Physics generates fundamental knowledge needed for the future technological advances that will continue to drive the economic engines of the world. 3) Physics contributes to the technological infrastructure and provides trained personnel needed to take advantage of scientific advances and discoveries.
8. 8. 4) Physics is an important element in the education of chemists, engineers and computer scientists, as well as practitioners of the other physical and biomedical sciences. 5) Physics extends and enhances our understanding of other disciplines, such as the earth, agricultural, chemical, biological, and environmental sciences, plus astrophysics and cosmology - subjects of substantial importance to all peoples of the world. 6) Physics improves our quality of life by providing the basic understanding necessary for developing new instrumentation and techniques for medical applications, such as computer tomography, magnetic resonance imaging, positron emission tomography, ultrasonic imaging, and laser surgery.
9. 9. The Strong Force A force which can hold a nucleus together against the enormous forces of repulsion of the protons is strong indeed. However, it is not an inverse square force like the electromagnetic force and it has a very short range. Yukawa modeled the strong force as an exchange force in which the exchange particles are pions and other heavier particles. The range of a particle exchange force is limited by the uncertainty principle. It is the strongest of the four fundamental forces.
10. 10. One of the four fundamental forces, the electromagnetic force manifests itself through the forces between charges (Coulomb's Law) and the magnetic force, both of which are summarized in the Lorentz force law. Fundamentally, both magnetic and electric forces are manifestations of an exchange force involving the exchange of photons. The quantum approach to the electromagnetic force is called quantum electrodynamics or QED. The electromagnetic force is a force of infinite range which obeys the inverse square law, and is of the same form as the gravity force. The Electromagnetic Force
11. 11. The Weak Force One of the four fundamental forces, the weak interaction involves the exchange of the intermediate vector bosons, the W and the Z. Since the mass of these particles is on the order of 80 GeV, the uncertainty principle dictates a range of about 10- 18 meters which is about .1% of the diameter of a proton. The weak interaction changes one flavor of quark into another. For example, in the neutron decay depicted by the Feynman diagram at left above, one down quark is changed to an up quark, transforming the neutron into a proton.
12. 12. The Gravitational Force It is the force of mutual attraction between two bodies by the virtue of their masses. Related by- It is a universal attractive force. It obeys inverse square law. It is the weakest force in nature. It is conservative, central and long range force. It is caused due to the exchange of particle called Graviton. 2 21 r mm GF
13. 13. Law Of Conservation Of Energy Conservation of energy implies that energy can be neither created nor destroyed, although it can be changed from one form (mechanical, kinetic, chemical, etc.) into another. In an isolated system the sum of all forms of energy therefore remains constant. For example, a falling body has a constant amount of energy, but the form of the energy changes from potential to kinetic. According to the theory of relativity, energy and mass are equivalent. Thus, the rest mass of a body may be considered a form of potential energy, part of which can be converted into other forms of energy.
14. 14. Law Of Conservation Of Linear Momentum Conservation of linear momentum expresses the fact that a body or system of bodies in motion retains its total momentum, the product of mass and vector velocity, unless an external force is applied to it. In an isolated system (such as the universe), there are no external forces, so momentum is always conserved. Because momentum is conserved, its components in any direction will also be conserved. Application of the law of conservation of momentum is important in the solution of collision problems. The operation of rockets exemplifies the conservation of momentum: the increased forward momentum of the rocket is equal but opposite in sign to the momentum of the ejected exhaust gases.
15. 15. Law Of Conservation Of Angular Momentum Conservation of angular momentum of rotating bodies is analogous to the conservation of linear momentum. Angular momentum is a vector quantity whose conservation expresses the law that a body or system that is rotating continues to rotate at the same rate unless a twisting force, called a torque, is applied to it. The angular momentum of each bit of matter consists of the product of its mass, its distance from the axis of rotation, and the component of its velocity perpendicular to the line from the axis.
16. 16. Law of Conservation of mass Conservation of mass implies that matter can be neither created nor destroyedi.e., processes that change the physical or chemical properties of substances within an isolated system (such as conversion of a liquid to a gas) leave the total mass unchanged. Strictly speaking, mass is not a conserved quantity. However, except in nuclear reactions, the conversion of rest mass into other forms of mass-energy is so small that, to a high degree of precision, rest mass may be thought of as conserved.
17. 17. Law Of Conservation Of Charge Conservation of charge states that the total amount of electric charge in a system does not change with time. At a subatomic level, charged particles can be created, but always in pairs with equal positive and negative charge so that the total amount of charge always remains constant. In particle physics, other conservation laws apply to certain properties of nuclear particles, such as baryon number, lepton number, and strangeness. Such laws apply in addition to those of mass, energy, and momentum encountered in everyday life and may be thought of as analogous to the conservation of electric charge.
18. 18. Fundamental units The physical quantities which can be treated as independent of other physical and are not usually defined in terms of other physical quantities are called physical quantities. Such as- STANDARD MEASURES
19. 19. Quantity Unit Symbol Length meter m Mass kilogram kg Temperature kelvin K Time second s Amount of Substance mole mol Luminous Intensity candela cd Electric Current ampere a
20. 20. Derived units The physical quantities whose defining operations are based on other physical quantities are called as derived units. Such as- speed (v) = distance / time * unit: m/s acceleration (a) = velocity / time * unit: m/s/s = m/s2 force (F) = mass x acceleration *unit: kgm/s2 energy (E) = force x distance *unit: kgm2/s2 = Nm=J charge (Q) = current x time *unit: As = C
21. 21. SYSTEM OF UNITS I. cgs system- Set up in France. It is based on centimeter, gram and second as the fundamental units of length, mass and time respectively. II. fps system- It is a British system based on foot, pound and second as the fundamental units of length, mass and time respectively.
22. 22. III.mks system- It is also a French system based on meter, kilogram and second as the fundamental units of length, mass and time respectively. IV. SI: The international system of units- It is a metric system of units consisting of seven base quantities length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity and two supplementary units- plane angle and solid angle
23. 23. Advantages of SI 1. SI is a coherent system of units i.e system based on a certain set of fundamental units, from which all derived units are obtained by multiplication or division without introducing numerical factors. 2. SI is a rational system of units as it assigns only one unit to be a particular physical quantity. For example, joule is the unit for all types of energy. This is not so in other systems of units.
24. 24. 3. SI is an absolute system of units. There are no gravitational units on the system. This use factor g is thus eliminated. 4. SI is a metric system i.e the multiples and sub multiples of units are expressed as power of 10. 5. In current electricity, the absolute units on the SI, like ampere for current, volt for potential difference, ohm for resistance, Henry for inductance, farad for capacity and so on.
25. 25. 1. Meter (m) 2. Second (s) 3. Kilogram (kg) 4. Kelvin (K) 5. Ampere (A) 6. Candela (cd) 7. Mole (mol) = 6.02 x 1023
26. 26. Unit of length (meter) The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second. The 1889 definition of the meter, based on the international prototype of platinum-iridium, was replaced by the 11th CGPM (1960) using a definition based on the wavelength of krypton 86 radiation. This change was adopted in order to improve the accuracy.
27. 27. Unit of mass (kilogram) The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram. The international prototype of the kilogram, an artifact made of platinum-iridium, is kept at the BIPM under the conditions specified by the 1st CGPM in 1889 (CR, 34-38) when it sanctioned the prototype and declared: This prototype shall henceforth be considered to be the unit of mass.
28. 28. Unit of time (second) The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. The unit of time, the second, was at one time considered to be the fraction 1/86 400 of the mean solar day. The exact definition of mean solar day was left to the astronomers. However measurements showed that irregularities in the rotation of the Earth made this an unsatisfactory definition
29. 29. Unit of electric current (ampere) The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross- section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 107 newton per meter of length.
30. 30. Unit of thermodynamic temperature (kelvin) The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. Because of the manner in which temperature scales used to be defined, it remains common practice to express a thermodynamic temperature, symbol T, in terms of its difference from the reference temperature T0 = 273.15 K, the ice point.
31. 31. Unit of amount of substance (mole) 1. The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is mol. 2. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.
32. 32. Unit of luminous intensity (candela) The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian. It follows that the spectral luminous efficacy for monochromatic radiation of frequency of 540 1012 hertz is exactly 683 lumens per watt, K(555) = 683 lm/W = 683 cd sr/W (the wavelength of radiation of this frequency is about 555 nm).
33. 33. Math and Units
34. 34. Determination of Diameter of Moon Let moon be the astronomical object of diameter D. Let E be the point on earth's surface. A telescope is focused on moon's surface and its image is observed as shown in figure is measured. S is the distance between moon and the Earth's surface. The diameter AB of moon is considered as a circular arc of radius S. Diameter of the moon can be found by knowing q and S. This above formula holds good only if S is very large and D can be considered as a small arc of radius S.
35. 35. Determination of distance of moon from earth (by parallax method) Let the object O be viewed with our eyes which is at a distance of r, making an angle between the two eyes as shown in the diagram. The angle q, caused by the two lines drawn from the position of the two eyes to the object, is called angle of parallax. If we can consider OA and OB as radius of a circle and the distance x (AB) as arc of the circle, then we have.
36. 36. However, if we consider O, referred in the above diagram to be the moon or a nearby star, then the angle q is too small in the view of the large astronomical distance and the place of observation. Hence, in order to have a better and valid point of observation, two points on the surface of the Earth is taken as the basis for observation instead of the two eyes. In order to have simultaneous observation of the moon, we select a very distant star at O and measure the angle between O and the two points on the Earth, as shown in the diagram below
37. 37. To Determine the Height of an Electric Pole Let AB be an electric pole, standing upright, on the ground. Let the point C be the observation point i.e., the observer standing. Therefore, BC is a horizontal distance on the ground and angle is subtended between the base and the top of the electric pole. The point C is also called as the elevation of the electric pole and the distance from BC to the point between the point of observation and the foot of the electric pole is x and 'h' is one height of the electric pole.
38. 38. i.e., h = x tan q, where the values of x and q could be known and the height of the electric pole be determined. This method is called Triangulation method.
39. 39. To Determine the Height using a Sextant AB and CD are two mirrors fixed, as in the diagram, parallel to each other and facing each other, i.e., the reflection on CD is seen on AB. A small telescope and a vernier travelling over a scale, graduated in degrees, constitute the sextant. The sextant is fixed firmly to view the horizon, when the reading on the scale is zero, i.e., the reading when the horizon is seen through both the mirrors.
40. 40. The arm of the sextant is a rotated until the reflected image of the sun is seen while the horizon is still seen directly, as in figure. Then, the angle between the horizontal and CE is twice the angle through which the arm is rotated. Since the graduations on the scale is double the angle through which the arm is rotated, the direct setting gives the reading straightaway.
41. 41. To Determine the Height of an Inaccessible Mountain Let PQ be the symbolic representation of the mountain (h), inaccessible for direct measurement. Let A and B be two points of elevation subtending angles q1 and q2 of the top of the mountain at P. Since the distance AB is a known quantity, - a horizontal entity say x, applying trigonometry, we have,
42. 42. where the values of x, q1 and q2 are known as h is evaluated.
43. 43. To Measure the Distance of a Submarine (Echo Method) Ultrasonic waves are transmitted through the ocean and if on its path any submerged objects are encountered, then as per law, the waves are reflected back to the origin. The time of sending the wave and the time of receiving the reflected wave are worked out and the distance of the submerged object (submarine in this case) is worked out by the formula where s is the distance between the point of transmission, v is the velocity of sound waves sent and t is the total time taken by the waves to travel to and fro.
44. 44. The dimensions of a physical quantity are the powers to which the fundamental quantities are raised to represent that physical quantity. The equation which expresses a physical quantity in terms of the fundamental units of mass, length and time, is called dimensional equation. According to this principle of homogeneity a physical equation will be dimensionally correct if the dimensions of all the terms in the all the terms occurring on both sides of the equation are the same.
45. 45. Main uses of the dimensional analysis There are three main uses of the dimensional analysis- (a) To convert a unit of given physical quantities from one system of units to another system for which we use n2 = n1[M1/M2]a[L1/L2]b[T1/T2]c (b) To check the correctness of a given physical relation. (c) To derive a relationship between different physical quantities.
46. 46. Advantages of Dimensional Analysis Dimensional equations are used to validate the correctness of a physical equation. Dimensional equations are used to derive correct relationship between different physical quantities. Dimensional equations are used to convert one system of units to another. Dimensional equations are used to find the dimension of a physical constant.
47. 47. Limitations of Dimensional Analysis Dimensional analysis has no information on dimensionless constants. If a quantity is dependent on trigonometric or exponential functions, this method cannot be used. In some cases, it is difficult to guess the factors while deriving the relation connecting two or more physical quantities. This method cannot be used in an equation containing two or more variables with same dimensions. It cannot be used if the physical quantity is dependent on more than three unknown variables. This method cannot be used if the physical quantity contains more than one term, say sum or difference of two terms.
48. 48. For counting of the significant figure rule are as: All non- zero digits are significant figure. All zero between two non-zero digits are significant figure. All zeros to the right of a non-zero digit but to the left of an understood decimal point are not significant. But such zeros are significant if they come from a measurement. All zeros to the right of a non-zero digit but to the left of a decimal point are significant. All zeros to the right of a decimal point are significant. All zeros to the right of a decimal point but to the left of a non-zero digit are not significant. Single zero conventionally placed to the left of the decimal point is not significant. The number of significant figures does not depend on the system of units.
49. 49. ACCURACY The accuracy of a measurement is its relation to the true, nominal, or accepted value. It is sometimes expressed as a percentage deviation from the known value. The known or true value is often based upon reproducible measurements. PRECISSION A measure of how close a series of measurements are to one another. A measure of how exact a measurement is.
50. 50. Example: Accurate Not Precise Not Accurate Precise Accurate and Precise
51. 51. Random Error Any factors that randomly affect measurement of the variable across the sample. For instance, each persons mood can inflate or deflate performance on any occasion. Random error adds variability to the data but does not affect average performance for the group.
52. 52. Systematic Error Any factors that systematically affect measurement of the variable across the sample. Systematic error = bias. For instance, asking questions that start do you agree with right-wing fascists that... will tend to yield a systematic lower agreement rate. Systematic error does affect average performance for the group.
53. 53. Absolute Error: Mean of n measurements Absolute error ( a ) = amean - a1 Absolute error is simply the amount of physical error in a measurement. Absolute error is positive , negative or zero. In plain English: The absolute error is the difference between the measured value and the actual value. (The absolute error will have the same unit label as the measured quantity.)
54. 54. Relative Error: Relative error is the ratio of the absolute error of the measurement to the accepted measurement. The relative error expresses the "relative size of the error" of the measurement in relation to the measurement itself. When the accepted or true measurement isknown, the relative error is found using which is considered to be a measure of accuracy.
55. 55. Percentage Error It is the relative error measured in percentage. So, Percentage Error = mean absolute value/mean value X 100 =amean/amX100
56. 56. The relative error expressed in percent is called percentage error. The error is communicated in different mathematical operations as detailed below:
57. 57. 1 . 1KWH is unit of 1.Time 2. Power 3. Energy 4. Stress Ans- 3. Energy 2. Unit of Intensity of magnetic induction field is 1.N/Am 2. Tesla 3.Wb/m2 4. All above Ans- 4. All above
58. 58. 3. Which of the following has no units? 1. Thermal capacity 2. Magnetic susceptibility 3. Angular acceleration 4. Moment of a magnet Ans-2. Magnetic susceptibility 4.Which one of the following units is a fundamental unit? 1. watt 2. joule/sec 3. ampere 4. newton Ans- 3. ampere
59. 59. 5. kg m/sec is the unit of 1. Impulse 2. Angular acceleration 3 . Capacity of condenser 4. Acceleration. Ans- Impulse 6. Which of the following is a common unit of a physical quantity in M.K.S & S.I systems. 1. ampere 2.kelvin 3. mole 4. joule/sec Ans- 4. joule/sec
60. 60. 7. Which of the following is Unit of length? 1.Lunar Month 2. Kelvin 3. candela 4. Light year Ans- 4. Light year 8. rad / sec is the unit of 1.Angular displacement 2. Angular velocity 3. Angular acceleration 4. Angular momentum Ans- 3. Angular acceleration
61. 61. 9. Which of the following is not a unit of power . 1. Watt 2. joule/hr 3. Nm/sec 4.N/sec Ans- 4.N/sec 10. If the unit of force were 20N,that of power were 1MW and that of time were 1 millisecond then the unit of length would be a) 20m b)50m c) 100m d) 1000m Ans-b)50m
62. 62. 11. The physical quantity having units of mass is 1.Density 2.Momentum 3. Inertia 4. Moment of force Ans- 3. Inertia 12.A force 100N acts on a body.If the units of mass and length are doubled and unit of time is halved,then the force in the new system changes to a)160N b) 1.6 N c) 16N d) 1600N Ans-d) 1600N
63. 63. 13. The electric resistance of a conductor is 54 ohm. If the unit of mass and length are tripled, units of time and electric current are doubled .Then the value of new electric resistance. a)540 ohm b) 1080 ohm c) 1620 ohm d)1944 ohm Ans-d)1944 ohm 14.Which of the following is a derived unit ? 1. ampere 2. mole 3. candela 4. newton Ans-4. newton
64. 64. 15) The power of a motor is 150W.If the unit of force is doubled, unit of velocity is tripled what will be the new unit of power. a) 600W b)750W c) 900W d) 300w Ans- c) 900W 16. The fundamental unit which is common in F.P.S and M.K.S systems is 1. foot 2. sec 3.kilo gram 4. pound Ans- 2. sec