1. AFMC–Past papers PHYSICS - UNSOLVED PAPER - 2008

2. SECTION – A 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. Problem 01 Given in a meter bridge experiment; l2 = 240 cm, l1 = 120 cm, R = 2Ω. Then value of r will be 2 Ω 2.5 Ω 1 Ω 4 Ω

4. Problem 02 If the rms speed of a given gas at 0°C is 0.5 m/s, then what will be its velocity at 819°C? 2 m/s 0.5 m/s 1 m/s 1.5 m/s

5. Problem 03 A rocket of mass 120 kg is moving vertically up at 600 m/s such that gas is escaping at the rate of i kg per second. Find out acceleration of the rocket. 2 m/s2 5 m/s2 6 m/s2 10 m/s2

6. Problem 04 A block is released from an inclined plane of inclination 45°. Find out the acceleration of the block down the incline, if friction coefficient between block and the incline is 0.5. 6√2 m/s2 √2 m/s2 10 √2 m/s2 6/ √2 m/s2

7. Problem 05 In an n - p - n transistor, p acts as emitter base collector emitter or collector

8. Problem 06 The conversion of N2 to 02 was first discovered by Rutherford in the year 1919 1901 1921 1942

9. Problem 07 What will be the change in time period of a simple pendulum in a space where value of acceleration due to gravity decreases 10 times? Given T to be the time period at the surface of earth. T 10 T √10 5 T

10. Problem 08 In case of a satellite, if the area of coverage becomes 3 times than that for an antenna of height 200 m. The height of antenna which has the same coverage is 600 m 300 m 1200 m 900 m

11. Problem 09 When a small spherical ball is dropped in a viscous liquid filled in a glass tube its terminal velocity depends upon height of cylinder radius of glass tube radius of ball none of these

12. Problem 10 If units of force and length become 3 times then what will be the value of energy E = 81 J, in newunits? 81 J 9 J 729 J 700 J

13. Problem 11 A particle of mass m moves towards north at speed v collides perfectly inelastically with another particle of mass m moving toward east at same speed. The speed at which they move after collision is √2v v ( v / √2 ) √2 v

14. Problem 12 A rigid body rotating about a fixed axis at an angular velocity 20 rad/sec has kinetic energy 360 J. Moment of inertia of the body about the fixed axis is 1.8 kg-m2 18kg-m2 2.5 kg-m2 4 kg-m2

15. Problem 13 If mass is increased 4 times, then the time period of a magnetometer when suspended in earth's magnetic field becomes double quadruple half decreases 4 times

16. Problem 14 A string of length 2 m vibrated with a tuning fork forms four loops. The distance between two consecutive nodes is 0.2 m 0.5 m 2 m 1 m

17. Problem 15 The phase difference between the current and voltage is 45° 30° 50° 90°

18. Problem 16 At the minimum deviation position the angle between incident ray and refracted ray is 60°. Angle of deviation is 30° 60° 120° 180°

19. Problem 17 If resistance is halved (keeping all other parameters same), the heat produced across resistor becomes double quadruple halved no change image*

20. Problem 18 In the given figure, internal resistance of the cell is 2 Ω 2.5 Ω 1 Ω 1.5 Ω

21. Problem 19 Dimensional formula of stress is [ML-1T2] [ML-1T-2] [ML-1T-1 ] [MLT-2]

22. Problem 20 A train 200 m long enters at 5 m/s and exits at 3 m/s from a bridge 300 m long. The time taken by it is 125 s 500 s 250 s 100 s

23. Problem 21 A particle is projected vertically upwards at 30 m/s. The distance travelled in the 1st second of motion is 20 m 25 m 15 m 30 m

24. Problem 22 If 300 J of heat is given, then find outthe maxim l work that can be done. 200 J 150 J 100 J 300 J

25. Problem 23 For two particles performing SHM with phase difference 90° and same amplitude, if maximum velocity of 1st particle is v, then what will be the maximum velocity of 2nd particle. 2v 3v v v/2

26. Problem 24 In SHM, expression for acceleration can be -Aω2 sin (ωt) -Aω sin (ωt) Aω2 sin (ωt) Aω sin (t/ω)

27. Problem 25 Deflection power is maximum for Radio waves X-rays y-rays none of these

28. Problem 26 If volume of a body changes keeping length same then the value of Poisson's ratio will be 0.2 0.5 0.1 0.8

29. Problem 27 Thermionic emissions are related to conduction convection radiation none of these

30. Problem 28 if sink is at a temperature of -39°C and source 0°C, then efficiency will be 39.4% 14.2% 35.2% 45.5%

31. Problem 29 If maximum range of a projectile is 400 m, then what will be its maximum height ? 50 m 200 m 100 m 400 m

32. Problem 30 A particle moves in a circular motion with radius 10 m at 20 m/s. It is given an acceleration of 30 m/s2. Find out its resultant acceleration. 20 m/s2 50 m/s2 60 m/s2 25 m/s2

33. Problem 31 Wavelength of red light is 2000 A 5000 A 4000 A 6000 A

34. Problem 32 In a telescope of length 20 cm magnification is 9. fv and fe are respectively. 18,2 11,9 15,5 10,10

35. Problem 33 Wave produced in a sonometer wire is transverse - progessive longitudinal - progessive transverse - standing longitudinal -standing

36. Problem 34 The magnification of a simple microscope with focal length of eye piece 5 cm, and minimum distance of distinct vision 25 cm is 6 6/5 5 5/6

37. Problem 35 The speed at which mass becomes double that of rest mass is 0.87 c 0.6 c 0.8 c 0.5 c

38. Problem 36 Find out the force on the wire of length 2 cm. 2 x 10-8 N 3 x 10-8N 2 x 10-7 N 8 x 10-6 N

39. Problem 37 In a deflection magnetometer, the time period of a magnet is found to be 8 sec. If the magnetic moment of another magnet is 1/4 of the first one, what is the time period of the latter ? 8 sec 4 sec 2 sec 16 sec

40. Problem 38 How much work can be obtained from 100 calories of heat energy ? 100 J 420 J 42 J 4200 J

41. Problem 39 What is the escape velocity of earth ? 11 km/s 110 km/s 660 km/min 38600 km/hr

42. Problem 40 If the coil of a heater is cut to half, what would happen to heat produced ? doubled halved remains same becomes four times

43. Problem 41 Iron is used in the core of transformers because of high hysteresis loss, low permeability high hysteresis loss, high permeability low hysteresis loss, low permeability low hysteresis loss, high permeability

44. Problem 42 Two samples have half lives t and 21 respectively. After a time period of 6/, what would be the ratio of undecayed atoms in the two samples ? 1 : 4 1 : 2 1 : 8 1 : 1

45. Problem 43 If E energy is required to project a body with speed v, what is the energy required to give an initial speed of 2v to the body? E 2E 4E E/2

46. Problem 44 If decays into ^ N p , the other decay products are positron and neutrino neutron and antineutrino electron and neutrino electron and antineutrino

47. Problem 45 The energy needed to ionise a singly ionised He is -13.6 eV 13.6 eV 54.4 eV -54.4 eV

48. Problem 46 If in a tube of length /, one gets frequencies 3v1, 5v1 the tube is open at one end open at both the ends closed at both ends none of these

49. Problem 47 A particle covers 150m in 8th second starting from rest, its acceleration is 15 m/s2 20 m/s2 10 m/s2 8 m/s2

50. Problem 48 When radioactive decay takes place one gets only heavy particles and not electromagnetic waves one can get heavy and light particles one can get heavy and light particles with electromagnetic waves and antiparticles. one cannot get antiparticles

51. Problem 49 If an X-ray tube with copper target, produce Ka rays one has to give energy equal to that of Ka rays one can get X-rays at any accelerating potential of the electrons one has to give sufficient energy to ionise the electron from the K shell one gets only characteristic X-rays if energy is less than K level energy of copper.

52. Problem 50 In mass spectrometers the principle that is used is electrostatic force only Lorentz force gravitational force all of these

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