1. IIT JEE –Past papers PHYSICS- UNSOLVED PAPER - 1987

2. SECTION – I Single Correct Answer Type In each of the statements given below, four alternatives are given. In some cases, more than one alternative is correct. Select the correct alternative(s) in each case and write down the corresponding letter(s)(a),(b),(c) or (d) in your answer book. For each part marks will be awarded only if all the correct alternatives are selected and written:

3. 01 Problem Four physical quantities are listed in column Their values are listed in column II in a random order. Column I Column II Thermal energy of air molecules at room temperature. 0.02 e V Binding energy of heavy nuclei per nucleon. 2 e V X-ray photon energy. 1 k e V Photon energy of visible light 7 Me V

4. Problem 02 The correct matching of columnsI and II is given by: (a)– (e), (b)-(h), (c)-(g), (d)-(f) (a)-(e), (b)-(g), (c)-(f), (d)-(h) (a)-(f), (b)-(e), (c)- (g), (d)-(h) (a)-(f), (b)-(h), (c)-(e), (d)-(g)

5. Problem 03 A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle. The motion of the particle takes place in a plane in a plane. It follows that: its velocity is constant its acceleration is constant its kinetic energy is constants it moves in a circular is path

6. Problem 04 A particle executes simple harmonic motion with a frequency, f. The frequency with which its kinetic energy oscillates is : f/2 f 2f 4f

7. Problem 05 A charge q is placed at the centre of the line joining two equal charge Q. The system of the three charges will be in equilibrium if q is equal to. a. b. c. d.

8. Problem 06 A parallel plate capacitor is charged and the charging battery is then disconnected. If the plates of the capacitor are moved farther apart disconnected. If the plates of the capacitor are moved farther apart by means of insulating handles: he charge on the capacitor increases The voltage across the plates increases The capacitance increases The electrostatic energy stored in the capacitor increases

9. Problem 07 Photoelectric effect supports quantum nature of light because: There is a minimum frequency of light below which no photoelectrons are emitted. The maximum kinetic energy of photoelectrons depends only on the frequency of light and not on its intensity Evan when the metal surface is faintly illuminated, the Photoelectrons leave the surface immediately Electric charge of the photoelectrons is quantized

10. Problem 08 During a negative beta decay: An atomic electron is ejected An electron which is already present within the nucleus is ejected A neutron in the nucleus decays emitting an electron A part of the binding energy of the nucleus is converted into an electron

11. Problem 09 During a nuclear fusion reaction: A heavy nucleus breaks into two fragments by itself. A light nucleus bombarded by thermal neutrons breaks up. A heavy nucleus bombarded by thermal neutrons breaks up. Two light nuclei combine to give a heaver nucleus and possibly other products

12. SECTION – II Fill in the blanks Fill in the blanks in the following statements. Indicate the subdivision number and write the answer corresponding to the blanks in your answer book.

13. 01 Problem A spotlight S rotates in horizontal plane with a constant angular velocity of 0.1 rad/s. The spot of light P moves along the wall at a distance of 3m. The velocity of the spot P when degrees (see Fig. 1987.1) is __________ m/s.

14. Problem 02 A geostationary satellite is orbiting the earth at a height of 6R above the surface of the earth, where R is the radius of the earth. The time period of another satellite at a height of 2.5R from the surface of the earth is _______ hours.

15. Problem 03 A particle of mass 4m which is at rest explodes into three fragments. Two of the fragments, each of mass m, are found to move with a speed v, each in mutually perpendicular directions. The total energy released in the process of explosion is _________.

16. Problem 04 A wire of length L and cross sectional area A is made of a material of Young’s modulus Y. If the wire is stretched by an amount x, the work done is _______.

17. Problem 05 In a son meter wire, the tension is maintained by suspending a 50.7 kg mass from the free end of the wire. The suspended mass has a volume of 0.0075 m3 . The fundamental frequency of vibration of the wire

18. Problem 06 A thin lens of refractive index 1.5 has a focal length of 15cm in air. When the lens is placed in a medium of refractive index , its focal length will become ________ cm

19. Problem 07 During an experiment, an ideal gas is found to obey an additional law VP2 = constant. The gas is initially at a temperature T, and volume V. When it expands to a volume 2V, the temperature becomes________.

20. Problem 08 An electric bulb rated for 500 W at 100 V is used in a circuit having a 200 V supply. The resistance R that one must put in series with the bulb to deliver 500W is ________ .

21. Problem 09 A wire of length L meters carrying a current amperes is bent in the form of a circle. The magnitude of its magnetic moment is _________ in MKS units

22. SECTION – III Each of which ether true or False State whether the following statements are true or false. Give reasons in brief in support of your answer. Marks will be awarded only if correct reasons are also given.

23. 01 Problem At a given temperature, the specific heat capacity of a gas at constant pressure is always greater than its specific heat capacity at constant volume.

24. Problem 02 The root means square (rms) speed of oxygen molecules (O2) at a certain temperature T (degree absolute) is V. If the temperature is doubled and oxygen gas dissociates into oxygen, the rms speed remain unchanged.

25. Problem 03 In a Young’s double slit experiment performed with a source of white light, only black and white fringes are observed.

26. Problem 04 A conducting rod AB moves parallel to the x-axis (see Fig. 1987.2) in a uniform magnetic field pointing in the positive z-direction. The end A of the rod gets positively charged.

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