PHYSICS
UPSC CSE Mains Physics Syllabus
(These syllabus may change from time to time. Please check with the relevant Public Service Commission websites for any changes in the syllabus)
Paper  I: 1. (a) Mechanics of Particles: Laws of motion; conservation of energy and momentum, applications to rotating frames, centripetal and Coriolis accelerations; Motion under a central force; Conservation of angular momentum, Kepler’s laws; Fields and potentials; Gravitational field and potential due to spherical bodies, Gauss and Poisson equations, gravitational selfenergy; Twobody problem; Reduced mass; Rutherford scattering; Centre of mass and laboratory reference frames. (b) Mechanics of Rigid Bodies: System of particles; Centre of mass, angular momentum, equations of motion; Conservation theorems for energy, momentum and angular momentum; Elastic and inelastic collisions; Rigid body; Degrees of freedom, Euler’s theorem, angular velocity, angular momentum, moments of inertia, theorems of parallel and perpendicular axes, equation of motion for rotation; Molecular rotations (as rigid bodies); Di and triatomic molecules; Precessional motion; top, gyroscope. (c) Mechanics of Continuous Media: Elasticity, Hooke’s law and elastic constants of isotropic solids and their interrelation; Streamline (Laminar) flow, viscosity, Poiseuille’s equation, Bernoulli’s equation, Stokes’ law and applications. (d) Special Relativity: MichelsonMorley experiment and its implications; Lorentz transformationslength contraction, time dilation, addition of relativistic velocities, aberration and Doppler effect, massenergy relation, simple applications to a decay process; Four dimensional momentum vector; Covariance of equations of physics. 2. Waves and Optics: (a) Waves: Simple harmonic motion, damped oscillation, forced oscillation and resonance; Beats; Stationary waves in a string; Pulses and wave packets; Phase and group velocities; Reflection and Refraction from Huygens’ principle. (b) Geometrical Optics: Laws of reflection and refraction from Fermat’s principle; Matrix method in paraxial opticsthin lens formula, nodal planes, system of two thin lenses, chromatic and spherical aberrations. (c) Interference: Interference of lightYoung’s experiment, Newton’s rings, interference by thin films, Michelson interferometer; Multiple beam interference and FabryPerot interferometer. (d) Diffraction: Fraunhofer diffractionsingle slit, double slit, diffraction grating, resolving power; Diffraction by a circular aperture and the Airy pattern; Fresnel diffraction: halfperiod zones and zone plates, circular aperture. (e) Polarization and Modern Optics: Production and detection of linearly and circularly polarized light; Double refraction, quarter wave plate; Optical activity; Principles of fibre optics, attenuation; Pulse dispersion in step index and parabolic index fibres; Material dispersion, single mode fibres; LasersEinstein A and B coefficients; Ruby and HeNe lasers; Characteristics of laser lightspatial and temporal coherence; Focusing of laser beams; Threelevel scheme for laser operation; Holography and simple applications. 3. Electricity and Magnetism: (a) Electrostatics and Magnetostatics: Laplace and Poisson equations in electrostatics and their applications; Energy of a system of charges, multipole expansion of scalar potential; Method of images and its applications; Potential and field due to a dipole, force and torque on a dipole in an external field; Dielectrics, polarization; Solutions to boundaryvalue problemsconducting and dielectric spheres in a uniform electric field; Magnetic shell, uniformly magnetized sphere; Ferromagnetic materials, hysteresis, energy loss. (b) Current Electricity: Kirchhoff’s laws and their applications; BiotSavart law, Ampere’s law, Faraday’s law, Lenz’ law; Selfand mutualinductances; Mean and r m s values in AC circuits; DC and AC circuits with R, L and C components; Series and parallel resonances; Quality factor; Principle of transformer. (c) Electromagnetic Waves and Blackbody Radiation: Displacement current and Maxwell’s equations; Wave equations in vacuum, Poynting theorem; Vector and scalar potentials; Electromagnetic field tensor, covariance of Maxwell’s equations; Wave equations in isotropic dielectrics, reflection and refraction at the boundary of two dielectrics; Fresnel’s relations; Total internal reflection; Normal and anomalous dispersion; Rayleigh scattering; Blackbody radiation and Planck’s radiation law, Stefan Boltzmann law, Wien’s displacement law and RayleighJeans’ law. 4. Thermal and Statistical Physics: (a) Thermodynamics: Laws of thermodynamics, reversible and irreversible processes, entropy; Isothermal, adiabatic, isobaric, isochoric processes and entropy changes; Otto and Diesel engines, Gibbs’ phase rule and chemical potential; van der Waals equation of state of a real gas, critical constants; MaxwellBoltzman distribution of molecular velocities, transport phenomena, equipartition and virial theorems; DulongPetit, Einstein, and Debye’s theories of specific heat of solids; Maxwell relations and applications; Clausius Clapeyron equation; Adiabatic demagnetisation, JouleKelvin effect and liquefaction of gases. (b) Statistical Physics: Macro and micro states, statistical distributions, MaxwellBoltzmann, BoseEinstein and FermiDirac distributions, applications to specific heat of gases and blackbody radiation; Concept of negative temperatures. PAPER  II: 1. Quantum Mechanics: Waveparticle dualitiy; Schroedinger equation and expectation values; Uncertainty principle; Solutions of the onedimensional Schroedinger equation for a free particle (Gaussian wavepacket), particle in a box, particle in a finite well, linear harmonic oscillator; Reflection and transmission by a step potential and by a rectangular barrier; Particle in a three dimensional box, density of states, free electron theory of metals; Angular momentum; Hydrogen atom; Spin half particles, properties of Pauli spin matrices. 2. Atomic and Molecular Physics: SternGerlach experiment, electron spin, fine structure of hydrogen atom; LS coupling, JJ coupling; Spectroscopic notation of atomic states; Zeeman effect; Frank Condon principle and applications; Elementary theory of rotational, vibratonal and electronic spectra of diatomic molecules; Raman effect and molecular structure; Laser Raman spectroscopy; Importance of neutral hydrogen atom, molecular hydrogen and molecular hydrogen ion in astronomy; Fluorescence and Phosphorescence; Elementary theory and applications of NMR and EPR; Elementary ideas about Lamb shift and its significance. 3. Nuclear and Particle Physics: Basic nuclear propertiessize, binding energy, angular momentum, parity, magnetic moment; Semiempirical mass formula and applications, mass parabolas; Ground state of deuteron, magnetic moment and noncentral forces; Meson theory of nuclear forces; Salient features of nuclear forces; Shell model of the nucleus  successes and limitations; Violation of parity in beta decay; Gamma decay and internal conversion; Elementary ideas about Mossbauer spectroscopy; Qvalue of nuclear reactions; Nuclear fission and fusion, energy production in stars; Nuclear reactors. Classification of elementary particles and their interactions; Conservation laws; Quark structure of hadrons; Field quanta of electroweak and strong interactions; Elementary ideas about unification of forces; Physics of neutrinos. 4. Solid State Physics, Devices and Electronics: Crystalline and amorphous structure of matter; Different crystal systems, space groups; Methods of determination of crystal structure; Xray diffraction, scanning and transmission electron microscopies; Band theory of solids  conductors, insulators and semiconductors; Thermal properties of solids, specific heat, Debye theory; Magnetism: dia, para and ferromagnetism; Elements of superconductivity, Meissner effect, Josephson junctions and applications; Elementary ideas about high temperature superconductivity. Intrinsic and extrinsic semiconductors; pn p and npn transistors; Amplifiers and oscillators; Opamps; FET, JFET and MOSFET; Digital electronicsBoolean identities, De Morgan’s laws, logic gates and truth tables; Simple logic circuits; Thermistors, solar cells; Fundamentals of microprocessors and digital computers. 1. When tennis ball is released with spin it becomes difficult to hit it back in the designed direction because
(A) we have to apply suitable torque (B) we have to apply suitable force (C) we have to apply suitable potential energy (D) we have to apply suitable kinetic energy Ans: A 2. The definition of kinetic energy for a rotating body about a fixed axis requires (A) Moment of inertia and angular velocity (B) Moment of inertia only (C) Angular velocity only (D) None of these Ans: A 3. A force acts on a body at rest and accelerates the same, then which of the following is true? (A) The greater the inertia the greater the acceleration (B) The greater the inertia the lesser the acceleration (C) The acceleration is independent of inertia (D) All of the three statements are incorrect Ans: B 4. Which of the following statement is true? (A) Torque plays the same role in rotational motion as force plays in translational motion (B) Torque does not play any role m rotational motion (C) Torque plays the same role in rotational motion as momentum plays in translational motion (D) Torque role is to keep the angular velocity constant Ans: A 5. A particle is going round a circular path with constant speed. Therefore it is moving with (A) Constant velocity (B) Constant acceleration (C) Constant momentum (D) None of these Ans: D 6. The force required to maintain a body at constant speed in free space is equal to (A) The kinetic energy of the body (B) Zero energy (C) The mass of the body (D) The weight of the body Ans: B 7. The moment of inertia of a ring is minimum about an axis (A) passing through its centre and perpendicular to its plane (B) passing through its edge and perpendicular to its plane (C) tangential in the plane of the ring (D) coinciding with diameter Ans: D 8. In a direct collision, the direction of motion of both the sphere is along the common normal at the point of contact? (A) before collision (B) after collision (C) before and after collision (D) none of the above Ans: C 9. The best example of impulse force is (A) a bullet hitting a target (B) a man pushing a cart (C) a boat being rowed (D) a car being towed Ans: A 10. Hooke's law obeys in the (A) Permanent set range (B) Elastic limit (C) Elastic range (D) Plastic range Ans: C 11. Poisson's ratio defines (A) ratio of longitudinal stress to linear strain (B) ratio of area stress to volume strain (C) ratio of tangential stress to shear strain (D) ratio of lateral strain to tangential strain Ans: D 12. In a cantilever as it is loaded at one end, the neutral filament of the beam (A) extends its length (B) shortens its length (C) remains constant (D) changes its length non uniformly Ans: C 13. Reynold number is used in the context of (A) Surface tension (B) Pressure ( C) Viscocity (D) Gravity Ans: C 14. Acceleration due to gravity for earth is (A) large at poles and small at equator (B) small at poles and large at equator (C) constant at poles and at equator (D) zero at poles and maximum at equator Ans: A 15. As the bore radius is reduced in a capillary rise method for a given liquid (A) height of the liquid column decreases (B) height of the liquid column increases (C) height of the liquid column remains constant (D) meniscus becomes concave to convex Ans: B 16. Angle of contact value for water with glass is (A) between 180° and 90° (B) greater than 90° and less than 140° (C) less than 90° and greater than 10° (D) less than 10° Ans: C 17. Consider the statements:
Assertion (A) : The osmatic pressure of electrolytes is much higher than that of nonelectrolytes under same temperature and concentration Reason (R): Dissociation of the electrolyte in solution. Select the answer according to coding scheme. (A) (A) and (R) are true (B) (A) and (R) are false (C) (A) is true but (R) is false (D) (A) is false but (R) is true Ans: A 18. The density of a gas is reduced to 1/4th of its value. The rate of diffusion (A) decreases four times (B) increases four times (C) decreases two times (D) increases two times Ans: D 19. When a substance is dissolved in a liquid, the boiling point of a liquid is (A) unchanged (B) raised (C) lowered (D) none of the above Ans: B 20. Which of the following is correct? The capillary rise method suffers from a number of drawbacks (A) The angle of contact is taken to be zero (B) The tube may not be of uniform area of cross section (C) The table may not be clean (D) All of the above Ans: D 21. The viscous force experienced by a falling sphere in a highly viscous liquid depends on (A) the terminal velocity of the ball (B) the radius of the ball (C) the coefficient of viscosity of the liquid (D) all of the above Ans: D 22. A physical process during which there is neither gain nor loss of heat from the system is called (A) adiabatic (B) isothermal (C) thermo dynamical (D) entropy Ans: A 23. The first law of thermodynamics is a statement which implies that
(A) no heat enters or leaves a system (B) the temperature remains constant (C ) all work is mechanical (D) energy is conserved Ans: D 24. The amount of heat energy radiated per second by a surface depends upon (A) area of the surface (B) difference of temperature between the surface and its surroundings (C ) nature of the surface (D) all the above Ans: D 25. If the pressure on the gas is increased from P to 2P atmosphere, then the heat conductivity (A) decreases (B) increases (C ) remains constant (D) decreases logarithmically Ans: C 26. If p  Calories of heat energy is incident on a body and absorb q  calories, its coefficient of absorption is (A) p/q (B) p  q (C) q /p (D) q + p Ans: A 27. When a body has the same temperature as that of its surroundings? (A) Both body do not radiate heat (B) It radiates same quantity of heat as it receives from surrounding (C) It radiates less quantity of heat as it receives from the surrounding (D) It radiates more quantity of heat as it receives from the surrounding Ans: D 28.The internal energy of a thermodynamical system consisting of an ideal gas is (A) Kinetic energy only (B) Potential energy only (C) Gravitational energy only (D) Partially kinetic and partially potential energy Ans: A 29. Critical temperature is one (A) above which the gaseous system remains the same (B) above which the gaseous system remains in liquid state (C) above which the gaseous system remains in solid state (D) below which the gaseous system remains the same Ans: A 30. Temperature of inversion means (A) Temperature above which temperature remaining constant (B) Temperature below which temperature is zero (C ) Temperature above which temperature increases (D) Critical temperature Ans: C 31. Refrigeration works as a (A) Carnot's engine in a heat engine (B) Carnot's engine in a reversible process (C ) Carnot's engine in an irreversible process (D) Carnot's engine without adiabatic process Ans: C 32. Third law of thermodynamics (A) entropy cannot be absolutely measured (B) at gaseous state, entropy is low compared that in the liquid state (C) at absolute zero temperature, entropy is zero (D) at absolute zero temperature, entropy is maximum Ans: C 33. When a train crosses a person standing on the platform, the pitch of the whistle of the train? (A) increases (B) decreases (C ) increases and then decreases (D) decreases and then increases Ans: C 34. In a sonometer, a particular length vibrates at a frequency. If the frequency of the same length is to be doubled, the tension of the string must be (A) decreased by a factor of two (B) decreased by a factor of four (C) increased by a factor of two (D) increased by a factor of four Ans: D 35. A stretched string of length 92 cm is divided into three segments whose frequencies are in the ratio 1 : 3 : 5. Then their lengths are in the ratio (A) 12 cm, 20 cm, 60 cm (B) 20 cm, 60 cm, 12 cm (C) 20 cm, 12 cm, 60 cm (D) 60 cm, 20 cm, 12 cm Ans: D 36. Very small differences in frequencies can be measured using (A) Resonance (B) Doppler effect (C) Ultrasonics (D) Beats Ans: D 37. Doppler shift in frequencies is due to the observer receiving the waves (A) ahead of time (B) behind time (C) ahead of or behind time (D) in time Ans: C In Frenel form of diffraction, the distance between be screen and the obstacle is
(A) zero (B) infinite (C) finite (D) none of the above Ans: C In case of Fraunhofer diffraction, we get fringed image of (A) source (B) obstacle (C) aperture (D) none of the above Ans: A 38. For good accoustics of a hall (A) time of reverberation be large (B) time of reverberation be small (C) time of reverberation be zero (D) time of reverberation be infinite Ans: B 39. The capacitance of the cylindrical capacitor is directly proportional to (A) length of the condenser (B) radius of the condenser (C) distance between coaxial cylinder (D) diameter of the condenser Ans: A 40. What is the potential at three different points (A, B, C) in equipotential surface? (A) A is greater than B and C (B) B is greater than C and A (C) C is greater than A and B (D) Equal in A, B and C Ans: D 41. Heat produced in an electric conductor is (A) directly proportional to its resistance (B) inversely proportion to its resistance (C) inversely proportional to the current (D) inversely proportional to square of the current Ans: A 42. The best instrument for the accurate measurement of the E.M.F. of a cell is (A) voltmeter (B) ammeter (C) potentiometer (D) Galvanometer Ans: C 43. Newton's rings are (A) diffraction bands (B) diffraction bands and interference fringes (C) interference fringes (D) none of the above Ans: C 44. In Frenel form of diffraction, the distance between be screen and the obstacle is (A) zero (B) infinite (C) finite (D) none of the above Ans: C 45. In case of Fraunhofer diffraction, we get fringed image of (A) source (B) obstacle (C) aperture (D) none of the above Ans: A 46. A device which produces plane polarized light is called
(A) polarizer (B) detector (C) analyser (D) none of the above Ans: A 47. Nicol prism is made by (A) Calcite crystal (B) Bauxite crystal (C) KCl crystal (D) None of the above Ans: A 48. The phenomenon of rotating the plane of vibration of polarised light when passed through the substance is known as (A) Polarisation (B) Optical activity (C) Double refraction (D) None of the above Ans: B 49. As a result of interference between two waves, energy is (A) lost (B) created at certain points and destroyed at others (C) created (D) redistributed Ans: D 50. Of the two statements given below, one is Assertion statement; the other is Reason. Study them, and select a suitable answer using the codes given below : Assertion (A) Information obtained from Hubble space telescope show that universe, as a whole is expanding. Reason (R) The colour of the distant star and appeared red on earth, showing a shift towards lower frequency of spectrum. (A) (A) is true, but (R) is not the reason for it. (B) (A) not true (C ) (A) is true and (R) is the reason for it (D)(R) not true Ans: C 51. One of the devices to produce plane polarised light is (A) a nicol prism (B) a crystal (C) a biprism (D) a half wave plate Ans: A 52. Optically active substances are those substances which (A) produce polarised light (B) rotate the plane of polarisation of polarised light (C) produce double refraction (D) convert a plane polarised light Ans: B 53. Polarisation of light proves the (A) Corpuscular nature of light (B) Quantum nature of light (C ) Transverse wave nature of light (C) Longitudinal wave nature of light Ans: C 54. In double slit experiment, for light of which colour the fringe width will be minimum? (A) Violet (B) Red (C) Green (D) Yellow Ans: A 55. In Raman effect, the scattered light contains (A) original wavelength only (B) original wavelength and increased wavelength (C) original wavelength and decreased wavelength (D) original wavelength and both increased and decreased wavelengths Ans: D 56. The characteristic property of a laser beam is (A) Coherent beam only (B) Monochromatic beam only (C) A diverging beam only (D) Coherent and monochromatic both Ans: D 57. The transition involving electro magnetic radiation are possible between two energy levels due to (A) Induced absorption emission only (B) Spontaneous emission only (C) Stimulated emission only (D) All the above Ans: D 58. For recording an ultra violet spectrum of shorter wavelength (A) Plane Transmission grating is used (B) Concave reflection grating is used (C) Crystal is used (D) Prism is used Ans: B 59. When ultra violet light is used for illumination, (A) the resolving power of a telescope is increased (B) the resolving power of a telescope is decreased (C) the resolving power of a microscope is decreased (D) the resolving power of a microscope is increased Ans: D 60. Globar filament is a rod made of ________ (A) rare earth oxides (B) carborundum (C) copper (D) semiconductor Ans: B 61. In IR spectrometer lenses and mirrors are made of (A) quartz (B) glass (C) mineral salt (D) calcite Ans: C 62. A radical is Raman active, if there is a change in of the molecule during the application of an electric field (A) dipole moment (B) electrical polarizability (C) bond length (D) bond angle Ans: B 63. If a molecule has a centre of symmetry, then Raman active vibrations are  (A) IR active (B) IR inactive (C) Microwave active (D) Microwave inactive Ans: B 64. The quality factor  Q of a laser cavity measure (A) gain (B) losses (C) broadening (D) population inversion Ans: B 65. The pumping process is Ruby laser is by (A) Optical means (B) Electrical means (C) Chemical means (D) Gas dynamic means Ans: A 66. The role of He atoms in He  Ne laser is to assist in the (A) pumping process (B) laser action (C) laser oscillation (D) population inversion Ans: A 67. The dynamo dissipates 20 watt when it supplies a current of 4 ampere through it. The terminal potential difference is 220V. The e.m.f. produced by the dynamo is (A) 220 V (B) 225V (C) 230 V (D) 240 V Ans: B 68. When a material is used in a magnetic field B, a magnetic moment proportional to B but opposite in direction is induced. The material is (A) Diamagnetic (B) Paramagnetic (C) Ferromagnetic (D) Antimagnetic Ans: A 69. When two equal and perfectly elastic spheres impinge directly, (A) their velocities remain unchanged (B) their velocities are changed (C) their velocities are interchanged (D) none of the above Ans: C 70. You are travelling in a car during a thunderstorm. In order to protect yourself from
lightning would you prefer to (A) remain in the car (B) take shelter under a tree (C) get out and lie flat on the ground (D) touch the nearest electric pole Ans: A 71. The resistance of 20 cm long wire is 5 ohms. The wire is stretched to a uniform wire of 40 cm length. The resistance now will be (in ohms) (A) 5 (B) 10 (C) 20 (D) 200 Ans: C 72. By electrostatic induction (A) only positive charge can be produced (B) only negative charge can be produced (C) any charge can be produced (D) any charge can be induced Ans: D 73. Paramagnetism is the property of (A) paired electrons (B) filled electronic sub shells (C) unpaired electrons (D) vacant electronic subshells Ans: C 74. A point source emits sound equally in all directions in a nonabsorbing medium. Two points P and Q are at distance of 2m and 3m respectively from the source. The ratio of the intensities of the waves at P and Q is :
1) 9 : 4 2) 2 : 9 3) 9 : 2 4) 4 : 9 Ans: 1 75. A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is 6 ms1. The kinetic energy of the other mass is : 1) 243 J 2) 486 J 3) 564 J 4) 388 J Ans: 2 76. A drum of radius R and mass M, rolls down without slipping along an inclined plane of angle θ. The frictional force : 1) converts translational energy to rotational energy 2) dissipates energy as heat 3) decreases the rotational motion 4) decreases the rotational and translational motion Ans: 1 77. Imagine a new planet having the same density as that of earth but it is 3 times bigger than the earth in size. If the acceleration due to gravity on the surface of earth is g and that on the surface of the new planet is g', then : 1) g' = 3g 2) g' = g/9 3) g' = 9g 4) g' = g/3 Ans: 1 78. Which of the following circular rods, (given radius r and length l) each made of the same material and whose ends are maintained at the same temperature will conduct most heat ? 1) r = 2r0; l = 2l0 2) r = 2r0; l = l0 3) r = r0; l = l0 4) r = r0; l = 2l0 Ans: 2 79. In the reaction 21H + 31H → 42He + 10n, if the binding energies of 21H, 31H and 42He are respectively a, b and c (in MeV), then the energy (in MeV) released in this reaction is : 1) c + a  b 2) c  a  b 3) a + b + c 4) a + b  c Ans: 2 80. Energy levels A, B and C of a certain atom correspond to increasing values of energy i.e., EA < EB < EC. If λ1, λ2 and λ3 are wavelengths of radiations corresponding to transitions C to B, B to A and C to A respectively, which of the following relations is correct ? 1) λ3 = λ1 + λ2 2) λ3 = (λ1λ2)/(λ1 + λ2) 3) λ1 + λ2 + λ3 = 0 4) λ23 = λ21 + λ22 Ans: 2 81. The work functions for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein's equation, the metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are : 1) none 2) A only 3) A and B only 4) all the three metals Ans: 3 82. The nuclei of which one of the following pairs of nuclei are isotones ? 1) 34Se74, 31Ga71 2) 42Mo92, 40Zr92 3) 38Sr84, 38Sr86 4) 20Ca40, 16S32 Ans: 1 83. The circular motion of a particle with constant speed is :
1) simple harmonic but not periodic 2) periodic and simple harmonic 3) neither periodic nor simple harmonic 4) periodic but not simple harmonic Ans: 4 84. A particle executing simple harmonic motion of amplitude 5 cm has maximum speed of 31.4 cm/s. The frequency of its oscillation is : 1) 2 Hz 2) 1.5 Hz 3) 0.5 Hz 4) 1 Hz Ans: 4 85. The ratio of the dimensions of Planck's constant and that of the moment of inertia is the dimension of : 1) frequency 2) velocity 3) angular momentum 4) time Ans: 1 86. Which of the following processes is reversible ? 1) Transfer of heat by radiation 2) Electrical heating of a nichrome wire 3) Transfer of heat by conduction 4) Isothermal compression Ans: 4 87. The temperature of inversion of a thermocouple is 620°C and the neutral temperature is 300°C. what is the temperature of cold junction ? 1) 20°C 2) 120°C 3) 20°C 4) 120°C Ans: 3 88. A photosensitive metallic surface has work function, hv0. If photons of energy 2hv0 fall on this surface, the electrons come out with a maximum velocity of 4 x 106 m/s. When the photon energy is increased to 5hv0, then maximum velocity of photoelectrons will be : 1) 16 x 106 m/s 2) 8 x 107 m/s 3) 4 x 105 m/s 4) 8 x 106 m/s Ans: 4 89. Fission of nuclei is possible because the binding energy per nucleon in them : 1) increases with mass number at high mass numbers 2) decreases with mass number at high mass numbers 3) increases with mass number at low mass numbers 4) decreases with mass number at low mass numbers Ans: 2 90. Application of a forward bias to a pn junction : 1) increases the number of donors on the nside 2) increases the electric field in the depletion zone 3) increases the potential difference across the depletion zone 4) widens the depletion zone Ans: 1 91. The displacement x of a particle varies with time t as x = aeαt + beβt, where a, b, α and β are positive constants. The velocity of the particle will : 1) go on decreasing with time 2) be independent of α and β 3) drop to zero when α = β 4) go on increasing with time Ans: 4 92. In any fission process the ratio (mass of fission products/mass of parent nucleus) is : 1) less than 1 2) greater than 1 3) equal to 1 4) depends on the mass of parent nucleus Ans: 1 93. If a vector 2î + 3ĵ + 8 is perpendicular to the vector 4ĵ  4î + α , then the value of α is : 1) 2 2) 1/2 3) (1/2) 4) 2 Ans: 3 94. Zener diode is used for : 1) producing oscillations in an oscillator 2) amplification 3) stabilisation 4) rectification Ans: 3 95. A stone tied to the end of a string of 1 m long is whirled in a horizontal circle with a constant speed. If the stone makes 22 revolutions in 44 s, what is the magnitude and direction of acceleration of the stone ?
1) (π2/4) ms2 and direction along the radius towards the centre 2) 2π2 ms2 and direction along the radius away from centre 3) π2 ms2 and direction along the radius towards the centre 4) 4π2 ms2 and direction along the tangent to the circle Ans: 3 96. If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by µd, µp and µf respectively, then : 1) µd ≠ 0 and µf ≠ 0 2) µp = 0 and µf ≠ 0 3) µd = 0 and µp ≠ 0 4) µd ≠ 0 and µp = 0 Ans: 3 97. In a circuit, L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by 45°. The value of C is : 1) (1)/(2πf(2πfL + R)) 2) (1)/(πf(2πfL + R)) 3) (1)/(2πf(2πfL  R)) 4) (1)/(πf(2πfL  R)) Ans: 3 98. The angular resolution of a 10 cm diameter telescope at a wavelength of 5000 Å is of the order of : 1) 106 rad 2) 104 rad 3) 104 rad 4) 106 rad Ans: 4 99. Two vibrating tuning forks produce progressive waves given by y1 = 4 sin 500 πt and y 2 = 2 sin 506 πt. Number of beats produced per minute is : 1) 360 2) 180 3) 120 4) 30 Ans: 2 100. When a wire of uniform crosssection a, length l and resistance R is bent into a complete circle, resistance between two of diametrically opposite points will be : 1) R/4 2) 2R 3) 4R 4) R/2 Ans: 1 
Recommended Books1. Universal SelfScorer Physics (English) (Set Of 2 Volumes)
2. Concepts of Physics 2 by H.C. Verma 3. 39 Years' Chapterwise Topicwise Solved Papers (20171979) IIT JEE Physics by DC Pandey 4. Concepts of Physics 1 by H.C. Verma 5. Handbook of Physics by Arihant Publications 6. Problems and Solutions in Physics for IIT JEE  Vol. 1 by McGraw Hill Education
