This document contains 50 physics problems with multiple choice answers. The problems cover topics such as potential difference in a potentiometer, transformer output voltage ratios, the cause of sky color and star twinkling, resistor combinations, logic gates, pressure as a force per unit area, velocity-time graphs, temperature scales, optics concepts like refraction and diffraction, semiconductor doping, radioactive decay types, lens and mirror formulas, circuit elements like resistors and capacitors, waves and sound, atomic structure, kinematics, and more. The correct answers are indicated by letters a, b, c or d for each problem.

1. AFMC–Past papersPHYSICS- UNSOLVED PAPER - 1995

2. SECTION – ASingle Correct Answer TypeThere 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. Problem01In figure the potentiometer wire AB has a resistance of 5Ω and length 10 m the balancing length AJ for the e.m.f of 0.4 V is0.8m4m0.4m1.5m

4. Problem02The primary winding of a transformer has 500 turns whereas its secondary has 5000 turns. The primary is connected to an AC supply 20 V, 50 Hz. The Secondary will have an output of2 v , 50 Hz200V, 50 Hz2V, 5Hz200V, 500Hz

5. Problem03The blue color of the sky is due to the phenomenon ofScattering ReflectionDispersionRefraction

6. Problem04The capacity of a parallel plate capacitor increases with theIncrease of its areaDecrease of its areaIncrease of its distanceNone of these

7. Problem05A student has 10 resistors of resistance r. The minimum resistance made by him from the give resistors isr/10010rr/5r/10

8. Problem06Which one of the following gates correspond to the truth table given belowNANDXORNOROR

9. Problem07Which of the following quantity is expressed as force per unit area?VolumeWorkAreaPressure

10. Problem08The displacement-time graph of a moving particle is shown below. The instantaneous velocity of the particle is negative as the pointEFCD

11. Problem09The equation constant. The unit of a isDyne/cm3Dyne/cm5Dyne x cm2Dyne x cm4

12. Problem10Water falls from a height of 800 m. if whole of its energy changes to heat, what would be the rise in its temperature when it reaches the ground (1 kcal=4200J)1.860c1.180c00c0.530c

13. Problem11The twinkling of stars is due to theRefractive index of the earth’s atmosphere fluctuatesFact that stars do not emit light continuously Both (a) and (b)None of these

14. Problem12At sun rise or sunset, the sun looks more red than at mid-day, because of theEffects of refractionSun is hottest at these timesEffects of diffractionScattering of light

15. Problem13The volume of atoms to the volume of nit cell is calledCoordination number Packing fractionLattice parameterPacking coefficient

16. Problem14a body moves due east with velocity 20km/hour and then due north with velocity 15 km/hour. The resultant velocity20 km/hour5 km/hour25 km/hour15 km/hour

17. Problem15A dip circle is at right angle to the magnetic meridian. What will be its apparent dip?600 00900300

18. Problem16Six resistors of 3Ω each are connected along the sides of a hexagon and three resistors of 6Ω each are connected along AC, AD and AE as shown in the figure. The equivalent resistance between A and B is equal to 2 Ω3 Ω6 Ω9 Ω

19. Problem17The direction of magnetic field line of bar magnet isAcross the bar magnet From south pole to north poleFrom south pole to north pole inside the magnet and from north pole to south pole outside the magnetFrom north pole to south pole

20. Problem18When Ge crystals are doped with phosphorus atom, then it becomesn-type semiconductorinsulator superconductorp-type semiconductor

21. Problem19In which radioactive disintegration, neutron dissociates into proton and electron?λ- emissionHe++ emission Positron emissionΒ-emission

22. Problem20The focal length of convex lens is 30cm and the distance of image is quarter of the object, then the object distance is40cm 90cm30cm60cm

23. Problem21When the number of turns and length of a solenoid are doubled, keeping the area of cross-section same, the inductanceIs doubledIs halvedBecomes four timesRemains the same

24. Problem22A solenoid is at potential difference of 60V. if the current flowing through it is 15 ampere, then resistance of the coil will be0.25 Ω4 Ω2 Ω8 Ω

25. Problem23Bending of light about the corner of an obstacle sharp edged is calledPolarizationDeviationDiffractionDispersion

26. Problem24If a source of light is moving away from a stationary observer, then frequency of light wave appears to change because ofDiffractionDoppler’s effectRefractionInterference

27. Problem25The reciprocal of resistance isVoltageConductanceCurrent Resistivity

28. Problem26In the case of forward biasing of p-n junction, which one of the following figures correctly depicts the direction of flow of carriers?a.b.c.d.

29. Problem27A galvanometer is converted into ammeter, when we connectLow resistance in series High resistance in series Low resistance in parallelHigh resistance in parallel

30. Problem28In an experiment with Kund’s tube the distance between consecutive nodes is 5 cm when air is inside, and it is 13.4 cm when hydrogen is inside calculate the velocity of sound in hydrogen(speed of sound in air = 330m/s)424m/s884.4 m/s1024.8 m/s864.4 m/s

31. Problem29The splitting of line into groups under the effect of electric or magnetic field is calledHeisenberg's effectBohr’s effectMagnetic effect Zeeman’s effect

32. Problem30Two open organ pipes of length 25 cm and 25.5 cm produce 0.1 beats/sec. the velocity of sound is303 m/s350 m/s255 m/s325.5 m/s

33. Problem31On the absolute scale of temperature given by Kelvin, steam point has a value of-273 K373 K0 K273 K

34. Problem32If the radius of curvature of convex mirror is 40 cm and distance of image is twice as that of object, then the object distance is30 cm60 cm20 cm40 cm

35. Problem33The minimum energy required to remove an electron is calledStopping potential Work functionPotential energy Kinetic energy

36. Problem34Two waves of the same frequency and intensity superimpose with each other in opposite phases after the superposition, theFrequency increases by 4 timesIntensity increases by 4 timesIntensity increases by two timesNone of these

37. Problem35The sensitivity of a tangent galvanometer is increased, ifField is increased Number of turns decreasedField is decreasedNumber of turns increased

38. Problem36The resistance of a wire is R. If the length of the wire is doubled, then its resistance will beR2R0.25 R4 R

39. Problem37Which of the following has a negative temperature coefficient?ManCAgFe

40. Problem38Radiation emitted by a surface is directly proportional toTwice power of its temperatureThird power of its temperatureEqual to its temperatureFourth power of its temperature

41. Problem39A rectangle ABCD is such that BC = 2 AB. The moment of inertia along axis will be minimum throughHFBCEGBD

42. Problem40In an isothermal expansion, the pressure is determined byCompressibility only Temperature onlyBoth (a) and (b)None of these

43. Problem41Monochromatic light wave means A beam of white colourA beam of the same colourA cluster of beam of different coloursNone of these

44. Problem42Time period of a simple pendulum will be double, if weDecrease the length 4 timesIncrease the length 4 timesDecrease the length 2 timesIncrease the length 2 times

45. Problem43Soap bubble appears coloured due to the phenomenon ofDispersion InterferenceReflectionDiffraction

46. Problem44The translational kinetic energy of gas, for one mole of the gas, is equal toa.b.c.d.

47. Problem45If we move from equator to pole, the value of gRemains the same Increases Decreases First (b) then (c)

48. Problem46If the critical temperature of CO2 is 31.10C and room temperature is 400C, then CO2 behaves asLiquid GasGas and vapourVapour

49. Problem47The minimum wavelength of the X-rays produced by electrons accelerated through a potential difference of V volts is directly proportional to1/√V√V 1/VV2

50. Problem48A bullet of mass 0.1 kg is fired with a speed of 100m/sec, the mass of gun is 50 kg. The velocity of recoil is0.5 m/sec0.2 m/sec0.05 m/sec0.1 m/sec

51. Problem49A hollow metallic sphere of radius 10 cm is charged such that potential of its surface is 70 volts. The potential at the centre of the sphere would be70V0V700V7V

52. Problem50A ball is thrown upwards with a velocity of 100m/sec. it will reach the ground after10 sec40 sec5 sec20 sec

53. For solution visit www.vasista.net