1. AMU PAST PAPERSPHYSICS- UNSOLVED PAPER - 1997

2. SECTION I Single Correct Answer Type There are five parts in this question. Four choices are given for each part and one of them is correct. Indicate you choice of the correct answer for each part in your answer-book by writing the letter (a), (b), (c) or (d) whichever is appropriate

3. 01 Problem A small telescope has an objective lens of focal length 150 cm and an eye piece of focal length 5 cm.The magnifying power of the telescope for viewing distant objects when the final image is formed at the least distance of distinct vision. a. 60 b. 45 c. 30 d. 36

4. 02 Problem Two thin lenses of same material and focal length f1 and f2 from an achromatic combination when the lenses are placed coaxially at a distance d apart so that : f1 f2 a. d = 2 f1f2 b. d = f1 f2 c. d = f1 f2- f1f2 d. d1 = f1 f2

5. 03 Problem A beam of light of wavelength 600nm from distant source falls on a single slit 1.0 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringe on either side of the central bright fringe is a. b. 2.4 mm c. 2.4 cm d. 1.2 cm e. 1.2 mm

6. 04 Problem In an interference pattern produced by the identical coherent sources of monochromatic light, the intensity at the site of central maxima is I. The intensity at the same sot when either of the two slits is closed is I0 then we must have a. I and I0 are not related b. I=4I0 c. I=I0 d. I=2I0

7. 05 Problem The temperature above which a ferromagnetic material becomes paramagnetic is called : a. Inversion temperature b. Debye temperature c. Critical temperature d. Curie temperature

8. 06 Problem Surface temperature of sun is estimated by measuring the wavelength at which the intensity of its emitted radiation is maximum and using : a. Wiens displacement law b. Stefans law c. Planck law d. Intensity y on Fraunhoffers lines

9. 07 Problem If unit of length, mass and time each be doubled the unit of work is increased by : a. 8 times b. 4 times c. 6 times d. 2 times

10. 08 Problem An elevator in which a man is standing is moving upwards with a speed of 190m/s. If the man drops a ball from a height of 2.45 m. It reaches the floor of the elevator after a time : a. 1 sec 2 b. 2 sec 1 c. 2 sec d. 2 sec

11. 09 Problem The time taken by the radio waves, to go and come back from a communication salellite to the earth is nearly a. 1 sec 1 b. 8 sec 1 c. 4 sec 1 d. 2 sec

12. 10 Problem What should be the angular speed of earth, so that bodies lying on equator may appear weightless? (take g=10 m/s2, and radius of earth R=6400 km) a. 1.25 x 10-3 rad/sec b. 0.62 x 10-3 rad/ssec c. 2.5 x 10-3 rad/sec d. none of these

13. 11 Problem (3 i 2 j 6k ) (14i 13 j 9k) A particle moves from post ions to position in meter and a uniform force (4 i j 3k ) N acts on it. The work done by the force will be : a. 150 J b. 50 J c. 80 J d. 100 J

14. 12 Problem A body of mass 2 kg is given a velocity of 10 m/s on a rough horizontal surface. If coefficient of friction is 0.2 and g=10 m/s2 . The body will stop after covering the distance of : a. 250 m b. 50 m c. 25 m d. 10 m

15. 13 Problem If the earth suddenly contracts to half its radius, what should be the length of the day ? by how much would the duration of the day be decreased? a. 6 hr, 18 hr b. 4 hr,20 hr c. 8 hr, 16 hr d. None of these

16. 14 Problem A rifle bullet losses 1/2oth of its velocity in passing through a plank, the least number of such planks required just to stop the bullet is : a. 22 b. 11 c. 10 d. 5

17. 15 Problem Which one of the graphs shows variation of magnetic induction with distance r from a long wire carrying current? a. b. c. d.

18. 16 Problem Two wire loops PORSP by joining two semicircular wires of radii R-1and R2 carrying current I as shown in figure. The magnitude of magnetic induction at centre is : 0 i 1 1 a. 4 R1 R2 0 i 1 1 b. 2 R1 R2 0 i 1 1 c. 4 R1 R2 0 i 1 1 d. 4 R1 R2

19. 17 Problem The number of electrons tube put on a spherical conductor of radius 0.1 m to produce an electric field of 0.036 N/C just above its surface is : a. 2.5 x 105 b. 2.8 x 105 c. 3 x 105 d. 3.2 x 105

20. 18 Problem A steady current of 5 amp is maintained for 45 minutes. During this time it deposits 4.572 g of zinc at the cathode of a voltammeter ECE of zinc is : a. 3.394 x 10-3 g coulomb b. 3.894 x 10-3 g coulomb c. 3.387 x 10-3 g coulomb d. None of these

21. 19 Problem A galvanometer of resistance 25 gives full scale deflection for current of 10 mA is to be changed into a voltmeter of range 100 V by connecting a resistance of R in series with galvanometer. The value of resistance is : a. 9975 b. 8975 c. 10020 d. 10000

22. 20 Problem If the number of turns in a coil becomes doubled then its self inductances will be: a. Unchanged b. Four times c. Halved d. Doubled

23. 21 Problem A current i is flowing in rectangular loop. It is put close in wire (long and straight) such that wire is parallel to one of the arms of loop and lies in the plane of loop. If a steady current I flows in the wire, the loop: a. Will remain steady b. Will move towards the wire c. Will move a away from the wire d. Will rotate about an axis parallel to wire

24. 22 Problem The numbers of turns of primary and secondary coils of transformer are 5 and 10 respectively and the mutual inductance of the transformer is 25 H. now the numbers of turns in the primary and secondary of the transformer are made 10 and 5 respectively. The mutual inductance of the transformer will be: a. 50henry b. 25henry c. 12.5henry d. 6.25henry

25. 23 Problem A wire of length L meter carrying a current I ampere is bent in the form of a circle. Its magnitude of magnetic moment will be: a. Li 2 4 i 2 L2 b. 4 iL2 c. 4 l d. L 4

26. 24 Problem A proton and an - particle are accelerated through the same potential difference the ratio of their de Broglie wavelengths p / will be: 1 a. 8 b. 8 c. 2 d. 1

27. 25 Problem Ultra violet light wavelength 3.00 nm and intensity 1.0 W/m2 falls on the surface of or photoelectric material. If one percent of incident photons produce photoelectrons. Then the number of photoelectron emitted from an area of 1.0 cm2of the surface is nearly: a. 2.13 x 1011/sec b. 1.52 x 1012/sec c. 3.02 x 1012/sec d. None of these

28. 26 Problem An -particle of 10 MeV colloids head on with copper nucleus (Z=29) and is deflected back. What s the maximum limit of radius of copper nucleus is ? a. 10.4x10-15 m b. 6.4x10-15 m c. 4.2x10-15 m d. 8.4x10-15 m

29. 27 Problem The ratio of energy of orbital electron in fourth and fifth orbit of hydrogen atom will be: a. 16:25 b. 4:5 c. 25:16 d. 5:4

30. 28 Problem A freshly prepared radioactive source of half life 2 hours emits radiation of intensity of which is 64 times the permissible safe level. The minimum time after which would be possible to work safely with this source is: a. 4 hrs b. 24 hrs c. 6 hrs d. 12 hrs

31. 29 Problem When a slow neutron is captured by a U235 nucleus. A fission result which releases 200 MeV energy. If the output of a nuclear reactor is 1.6 MW. The rate of nuclei undergoing fission, will be: a. 5x1016 b. 3x1066 c. 4x1016 d. None these

32. 30 Problem The dominant mechanism for motion of charge carries n forward and reverse biased silicon p-n junction is: a. Drift in both forward and reverse biased b. Diffusion in both forward and reverse biased c. Diffusion in forward biased and drift in reverse biased d. Drift in forward biased and diffusion in reverse biased

33. 31 Problem A radio waves of frequency 840 Hz is sent towards aeroplane. The frequency of 2.8 kHz more than the original frequency then velocity of aeroplane is : a. 0.5 km/sec b. 5 km/sec c. 0.25 km/sec d. None these

34. 32 Problem A transistor with = 0.95 is operated as an amplifier in a common base circuit with a load resistance of 5kW . If the dynamic resistance of the emitter base junction is 70 . The voltage gain and power gain of the circuit will be: a. 70,68.6 b. 72,70.6 c. 74,72.2 d. None these

35. 33 Problem A ideal gas expands according to the law PV2=constant. The value of molar heat capacity: a. Cv R Cv R b. 2 c. R- Cv d. None of these

36. 34 Problem Water falls through a height of 250 m. Assuming that whole of energy is converted into heat the rise in temperature of water will be: (g = 9.8 m/s2, J = 4.18 x103J/kilocal) a. 0.590C b. 1.590C c. 2.570C d. None of these

37. 35 Problem An electric bulbs of volume 25 cm3 was sealed off during manufacture at a pressure of 10-3 mm of Hg at 270C. The number of molecules in the bulb will be : a. 4x105 b. 6x105 c. 7.05x105 d. 8.05x105

38. 36 Problem The time period of a seconds pendulum is 2 sec .The spherical bob which is empty from inside has a mass 50 gram this now replaced by another solid of same radius but have different mass of 100 gram. The new time period will be: a. 2 sec b. 8 sec c. 4 sec d. 1 sec

39. 37 Problem Van de Graffe generator is used to: a. Compare high D.C. potential b. Produce high A.C. potential c. Measure high potential difference d. Produce high D.C. potential

40. 38 Problem The force between the plate of a charged parallel plate capacitor is: a. q2 F 2 0A b. F q 2 0A c. q2 F 0A d. none of these

41. 39 Problem A colour coded carbon resistor has the scheme (as shown in fig), then the colour coded resistance will be : a. 52000 10% b. 53000 10% c. 62000 10% d. none of these

42. 40 Problem A particle is particle is executing S.H.M., the potential energy of the particle is maximum at: a. Same at all position b. Midway between mean and extreme position c. Mean position d. Extreme position

43. 41 Problem Two perfect gases at absolute temperature T1 and T2 are mixed, there is so loss of energy then the temperature of the mixture if masses are m1 and m2 and the number of molecules are n1 and n2 respectively will be: a. n1T1 n2T2 n1 n2 b. n2T1 n1T2 2(n1 n2 ) n2T1 n1T1 c. n1 n2 n1T1 n2T2 d. n1 n2

44. 42 Problem At 27oC temperature, then mean kinetic energy per molecule of an ideal gas is E1. If the temperature is increased to 3270C the mean kinetic energy would be ; a. E1 2 2 b. E E1 c. 2 d. 2 E

45. 43 Problem The bulk modulus of water is 2x109N/m2 the change in pressure required to increases the density of water by 0.1% is: a. 2x104 N/m2 b. 2x106 N/m2 c. 2x108 N/m2 d. 2x109 N/m2

46. 44 Problem In a sinusoidal wave, the time required for a particle point to move from maximum displacement is 0.17 sec. The frequency of wave is: a. 2.94 Hz b. 1.97 Hz c. 0.73 Hz d. 0.36 Hz

47. 45 Problem 1 1 The mass f moon is 81 of the earths mass and its radius is 4 that of earth . If the escape velocity from the earths surface is 11.2 km/sec. The value of escape velocity on the moon will be: a. 5 km/s b. 2.5 km/s c. 7.5 km/s d. 2.1 km/s

48. 46 Problem The strong, electrostatic and gravitation forces are in the ratio: a. 1:10-8 :10-48 b. 1:104 :1040 c. 1:10-3 :10-30 d. 1:10-2 :10-34

49. 47 Problem The gravitational force is given by F 4k. The work done in transporting a mass of 2 kg from (0,0,0) to (4,3,5) m by a external source is : a. 15 J b. 10 J c. 50 J d. 20 J

50. 48 Problem A hammer weighing 2.5 kg moving with a speed of 1 m/s strikes the head of the nail driving it 10 cm into the wall. The acceleration during impact and the impulse imparted to wall will be respectively: a. -5m/s2, 2.5Ns b. -10m/s2, 5 Ns c. -7.5 m/s2, 3.5 Ns d. None of these

51. 49 Problem A projectile can have the same range for two angles of projection. If h1 and h2 are maximum heights when the range in the two cases is R, then the relation between R, h1 and h2 is : a. R = 4 h1 h2 b. R = 2 h1 h2 h1 h2 c. R = d. None of these

52. 50 Problem When the kinetic energy of a body is increased by three times, then the momentum increases: a. 6 times b. 1.732 times c. 2 times d. 3 times

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