1. IIT JEE –Past papers PHYSICS- UNSOLVED PAPER - 1994

2. SECTION – I Multiple correct Answer type In each part of this question four alternatives are given of which one or more alternative(s) is/are correct. Select the correct alternative(s) and write down the corresponding letters(s) a, b, c, d in your answer book against the sub-question number, marks will be awarded only if all the correct alternative(s), and no wrong alternatives are selected.

3. 01 Problem The magnitudes of the gravitational field at distances r1 and r2 from the center of a uniform sphere of radius R and mass M are F1 and F2 respectively. Then a. b. c. d.

4. Problem 02 Two different coils have self –inductances, L1 = 8 mH, and L2 = 2 mH. The current in one coil is increased at a constant rate. The current in the second coil is also increased at the same constant rate. At a certain instant of time, the power given to the two coils is the same. At that time the current, the induced voltage and the energy stored in the first coil are i1, v1, and w1 respectively. Corresponding values for the second coil at the same instant are i2, v2 and w2 respectively. Then a. b. c. d.

5. Problem 03 H+, He+ and O2+ all having the same kinetic energy pass through a region in which there is a uniform magnetic field perpendicular to their velocities. The masses of H+, He+ and O2+ are 1 amu, 4 amu and 16 amu respectively. The H+ will be deflected most O2+ will be deflected most He+ and O2+ will be deflected equally All will be deflected equally

6. Problem 04 When photons of energy 4.25e V strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy, TA (expressed in eV) and de Broglie wavelength, The maximum Kinetic energy of photoelectrons liberated from another metal B by photons of energy 4.70 eV is If the de Broglie wavelength of these photoelectrons is , then The work function of A is 2.25 eV The work function of B is 4.20 eV TA = 2.00 eV TB = 2.75 eV

7. Problem 05 Two bodies A and B have thermal emissivities of 0.01 and 0.81 respectively. The outer surface areas of the two bodies are the same, The two bodies emit total radiant power at the same rate. The radiation from B is shifted from the wavelength corresponding to maximum spectral radiancy in the radiation from A, by 1.00 m. If the temperature of A is 5802 K. The temperature of B is 1934 K B= 1.5 m The temperature of B is 11604 K The temperature of B is 2901 K

8. Problem 06 Which of the following statement (s) is/are correct? The rest mass of a stable nucleus is less than the sum of the rest masses of its separated nucleons The rest mass of a stable nucleus is greater than the sum of the rest masses of its separated nucleons In nuclear fusion, energy is released by fusing two nuclei of medium mass (approximately 100 amu) In nuclear fission, energy is released by fragmentation of a very heavy nucleus.

9. SECTION – II Fill in the blanks Fill in the blanks in the following. In your answer book, write down the sub-question number (I, ii , iii etc.) and your answer against it corresponding to each blank. Your answer should be in the sequence I, ii, etc. as given in the question paper

10. 01 Problem The magnitude of the force (in newtons) acting on a body varies with time t (in microseconds) as shown in the Fig. 1994.1 AB, BC, and CD are straight line segments. The magnitude of the total impulse of the force on the body from t = 4 s to t = 16 s is ___________________N.

11. Problem 02 An object of mass 0.2 kg executes simple harmonic oscillations along the x-axis with a frequency of (25/ ) Hz. At the position x = 0.04 m, the object has kinetic energy of 0.5 J and potential energy of 0.4 J. The amplitude of oscillations is _____________m.

12. Problem 03 An ideal gas with pressure P, volume V, and potential T is expanded isothermally to a volume 2V and a final pressure Pi. If the same gas is expanded adiabatically to a volume 2V, the final pressure is P=. The ratio of the specific heat capacities for the gas is 1.67. The ratio Pa/Pi is _____________________.

13. Problem 04 A bus is moving towards a huge wall with a velocity of 5 ms-1. The driver sounds a horn of frequency 200 Hz. The frequency of the beats heard by a passenger of the bus will be _________________ Hz. (Speed of sound in air = 342 m s-1)

14. Problem 05 A horizontal pipeline carries water in a streamline flow. At a point along the pipe where the cross-sectional area is 10 cm2, the water velocity is 1 m s-1 and the pressure is 2000 Pa. The pressure of water at another point where the cross-sectional area is 5 cm2, is ________________ Pa. (Density of water = 103 kg m-3.)

15. SECTION – III Single Correct Answer Type In each part of this question, a statement is followed by four alternatives of which only one alternative is correct. Select the correct alternative and write down the corresponding letter a, b, c, d in your answer book against the sub-question number. In your answers. The sequence of the sub-question should be the same as in the question paper

16. 01 Problem A block of mass 0.1 kg is held against a wall by applying a horizontal force of 5N on the block. If the coefficient of friction between the block and the wall is 0.5, the magnitude of the frictional force acting on the block is 2.5 N 0.98 N 4.9 N 0.49 N

17. Problem 02 Fast neutrons can easily be slowed down by The use of lead shielding Passing them through water Elastic collisions with heavy nuclei Applying a strong electric field

18. Problem 03 Spherical aberration in a thin lens can be reduced by Using a monochromatic light Using a doublet combination Using a circular annular mask over the lens Increasing the size of the lens

19. Problem 04 A particle of mass m is moving in a circular path of constant radius r such that its acceleration ac is varying with time t as where k is a constant. The power delivered to the particle by the force acting on it is a. b. c. ( 5)/3 d. zero

20. Problem 05 A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of the central bright fringe is 1.2 cm 1.2 mm 2.4 cm 2.4 mm

21. Problem 06 Consider particles, particles and -rays, each having energy of 0.5 MeV. In increasing order of penetrating powers, the radiations are a. b. c. d.

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