NEET AIPMT Physics Chapter Wise Solutions Archives

NEET AIPMT Physics Chapter Wise Solutions – Dual Nature of Radiation and Matter

NEET AIPMT Physics Chapter Wise Solutions Chemistry Biology

1. A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and If the maximum kinetic energy of the emitted photo electrons in the second case is 3 times that in the first case, the work function of the surface of the material is
(h = Planck’s constant, c = speed of light) (AIPMT 2015)

2. Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is (AIPMT 2015)

3. Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?

4. A certain metallic surface is illuminated with monochromatic light of wavelength, λ. The stopping potential for photo-electric current for this light is 3V₀. If the same surface is illuminated with light of wavelength 2A, the stopping potential is V. The threshold wavelength for this surface for photo-electric effect is (AIPMT 2015, Cancelled)

5. When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is (AIPMT 2014)
(a) 0.65 eV
(b) 1.0 eV
(c) 1.3 eV
(d) 1.5 eV

6. If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de Broglie wavelength of the particle is (AIPMT 2014)
(a) 25
(b) 75
(c) 60
(d) 50

7. The wavelength λ_e of an electron and λ_p of a photon of same energy E are related by (NEET 2013)

8. For photoelectric emission from certain metal the cutoff frequency is υ. If radiation’of frequency 2υ impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass) (NEET 2013)

9. A source of light is placed at a distance of 50 cm from a photo cell and the stopping potential is found to be V₀. If the distance between the light source and photo cell is made 25 cm, the new stopping potential will be : ( Karnataka NEET 2013)
(a) V
(b) V
(C) 4V
(d) 2V

10. The de-Broglie wavelength of neutrons in thermal equilibrium at temperature T is ( Karnataka NEET 2013)

11. A 200 W sodium street lamp emits yellow light of wavelength 0.6 μm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is (Prelims 2012)
(a) 1.5 x 10²⁰
(b) 6 x 10¹⁸
(c) 62 x 10²⁰
(d) 3 x 10¹⁹

12. Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is (Prelims 2012)
(a) 4 x 10¹⁵Hz
(b) 5 x 10¹⁵Hz
(c) 1.6 x 10¹⁵Hz
(d) 2.5 x 10¹⁵ Hz

13. An α-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m². The de Broglie wavelength associated with the particle will be (Prelims 2012)
(a) 1 Å
(b) 0.1 Å
(c) 10 Å
(d) 0.01 Å

14. If the momentum of an electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be (Mains 2012)
(a) 200P
(b) 400P
(c) P/200
(d) 100P

15. Two radiations of photons energies 1 eV and 2.5 eV, successively illuminate a photosensitive metallic surface of work function 0.5 eV. The ratio of the maximum speeds of the emitted electrons is (Mains 2012)
(a) 1:4
(b) 1:2
(c) 1:1
(d) 1:5

16. Photoelectric emission occurs only when the incident light has more than a certain minimum (Prelims 2011)
(a) power
(b) wavelength
(c) intensity
(d) frequency

17. In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by (Prelims 2011)
(a) increasing the potential difference between the anode and filament
(b) increasing the filament current
(c) decreasing the filament current
(d) decreasing the potential difference between the anode and filament

18. Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be (Prelims 2011)
(a) 1 : 4
(b) 1 : 2
(c) 1 : 1
(d) 1 : 5

19. Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV then the de-Broglie wavelength associated with the electrons would (Prelims 2011)
(a) increase by 2 times
(b) decrease by 2 times
(c) decrease by 4 times
(d) increase by 4 times

20. In photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. The corresponding stopping potential is (Prelims 2011)
(a) 1.8 V
(b) 1.3 V
(c) 0.5 V
(d) 2.3 V

21. The threshold frequency for a photosensitive metal is 3.3 x 10¹⁴ Hz. If light of frequency 8.2 x 10¹⁴ Hz is incident on this metal, the cut-off voltage for the photoelectron emission is nearly (Mains 2011)
(a) IV
(b) 2 V
(c) 3 V
(d) 5 V

22. A beam of cathode rays is subjected to crossed electric (E) and magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by (Prelims 2010)
(Where V is the potential difference between cathode and anode)

23. A source S₁ is producing, 10¹⁵ photons per second of wavelength 5000 Å. Another source S₂ is producing 1.02 x 10¹⁵ photons per second of wavelength 5100 A. Then, (power of S₂/(power of S₁) is equal to (Prelims 2010)
(a) 1.00
(b) 1.02
(c) 1.04
(d) 0.98

24. The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be (Prelims 2010 )
(a) 2.4 V
(b) -1.2 V
(c) -2.4 V
(d) 1.2 V

25. When monochromatic radiation of intensity I falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are N and T respectively. If the intensity of radiation is 2I, the number of emitted electrons and their maximum kinetic energy are respectively (Mains 2010)
(a) N and 2 T
(b) 2N and T
(c) 2V and 2T
(d) Vand T

26. The electron in the hydrogen atom jumps from excited state (n = 3) to its ground state (n = 1) and the photons thus emitted irradiate a photosensitive material. If the work function of the material is 5.1 eV, the stopping potential is estimated to be (the energy of the electron in nth
(Mains 2010)
(a) 5.1V
(b) 12.1V
(c) 17.2 V
(d) 7 V

27. The number of photo electrons emitted for light of a frequency υ (higher than the threshold frequency υ₀) is proportional to (Prelims 2009)
(a) threshold frequency (υ₀)
(b) intensity of light
(c) frequency of light (υ)
(d) υ – υ₀

28. The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement? (Prelims 2009)

(a) Curves (a) and (b) represent incident radiations of same frequency but of different intensities.
(b) Curves (b) and (c) represent incident radiations of different frequencies and different intensities.
(c) Curves (b) and (c) represent incident radiations of same frequency having same intensity.
(d) Curves (a) and (b) represent incident radiations of different frequencies and different intensities.

29. Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec. on the average at a target irradiated by this beam is (Prelims 2009)
(a) 3 x 10¹⁶
(b) 9 x 10¹⁵
(c) 3 x 10¹⁹
(d) 9 x 10¹⁷

30. The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the (Prelims 2008)
(a) Infrared region
(b) X-ray region
(c) Ultraviolet region
(d) Visible region

31. A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 x 10⁶ ms^-1. The velocity of the particle is
(Prelims 2008)

32. In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of (Prelims 2008)
(a) collisions between the charged particles emitted from the cathode and the atoms of the gas
(b) collision between different electrons of the atoms of the gas
(c) excitation of electrons in the atoms
(d) collision between the atoms of the gas

33. A beam of electron passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move (2007)
(a) in a circular orbit
(b) along a parabolic path
(c) along a straight line
(d) in an elliptical orbit.

34. Monochromatic light of frequency 6.0 x 10¹⁴ Hz is produced by a laser. The power emitted is 2 x 10^-3 W. The number of photons emitted, on the average, by the source per second is (2007)
(a) 5 x 10¹⁶
(b) 5 x 10¹⁷
(c) 5 x 10¹⁴
(d) 5 x 10¹⁵.

35. A 5 watt source emits monochromatic ligfft of wavelength 5000 Å. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m, the number of photoelectrons liberated will be reduced by a factor of (2007)
(a) 8
(b) 16
(c) 2
(d) 4.

36. A photocell employs photoelectric effect to convert (2006)
(a) change in the frequency of light into a change in the electric current
(b) change in the frequency of light into a change in electric voltage
(c) change in the intensity of illumination into a change in photoelectric current
(d) change in the intensity of illumination into a change in the work function of the photocathode.

37. When photons of energy hυ fall on an aluminium plate (of work function E₀), photoelectrons of maximum kinetic energy K are ejected. If the frequency of radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be (2006)
(a) K + hυ
(b) K + E₀
(c) 2K
(d) K.

38. In a discharge tube ionization of enclosed gas is produced due to collisions between (2006)
(a) neutral gas atoms/molecules
(b) positive ions and neutral atoms/molecules
(c) negative electrons and neutral atoms/molecules
(d) photons and neutral atoms/molecules.

39. The momentum of a photon of energy 1 MeV in kg m/s will be (2006)
(a) 5 x 10^-22
(b) 0.33 10⁶
(c) 7 x 10^-24
(d) 10^-22

40. The work functions for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein’s equation the metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are (2005)
(a) A only
(b) A and B only
(c) all the three metals
(d) none.

41. A photosensitive metallic surfacfe has work function, hυ₀. If photons of energy 2hυ₀ fall on this surface, the electrons come out with a maximum velocity of 4 x 10⁶ m/s. When the photon energy is increased to 5hυ₀, then maximum velocity of photoelectrons will be (2005)
(a) 2 x 10⁷ m/s
(b) 2 x 10⁶ m/s
(c) 8 x 10⁶ m/s
(d) 8 x 10⁵ m/s.

42. According to Einstein’s photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is

43. A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then (2003)
(a) each emitted electron carries one quarter of the initial energy
(b) number of electrons emitted is half the initial number
(c) each emitted electron carries half the initial energy
(d) number of electrons emitted is a quarter of the initial number

44. J.J. Thomson’s cathode-ray tube experiment demonstrated that (2003)
(a) cathode rays are streams of negatively charged ions
(b) all the mass of an atom is essentially in the nucleus
(c) the e/m of electrons is much greater than the elm of protons
(d) the e/m ratio of the cathode-ray particles changes when a different gas is placed in the discharge tube

45. The value of Planck’s constant is
(a) 6.63 x 10^-34 J/sec.
(b) 6.63 x 10^-34 kg-m²/sec
(c) 6.63 x 10^-34 kg-m²
(d) 6.63 x 10^-34 J-sec. (2002)

46. If particles are moving with same velocity, then which has maximum de Broglie wavelength? (2002)
(a) proton
(b) α-particle
(c) neutron
(d) β-particle.

47. When ultraviolet rays incident on metal plate then photoelectric effect does not occur, it occurs by incidence of (2002)
(a) infrared rays
(b) X-rays
(c) radio wave
(d) micro wave.

48. Which of the following is not the property of cathode rays? (2002)
(a) It produces heating effect
(b) It does not deflect in electric field
(c) It casts shadow
(d) It produces fluorescence.

49. Which one among the following shows particle nature of light? (2001)
(a) photo electric effect
(b) interference
(c) refraction
(d) polarization.

50.

51. A photo-cell is illuminated by a source of light, which is placed at a distance d from the cell. If the distance become d/2, then number of electrons emitted per second will be (2001)
(a) remain same
(b) four times
(c) two times
(d) one-fourth.

52. By photoelectric effect, Einstein proved (2000)

53. Who evaluated the mass of electron indirectly with help of charge (2000)
(a) Thomson
(b) Millikan
(c) Rutherford
(d) Newton.

54. When a proton is accelerated through 1 V, then its kinetic energy will be (1999)
(a) 1 eV
(b) 13.6 eV
(c) 1840eV
(d) 0.54 eV

55. The photoelectric work function for a metal surface is 4.125 eV. The cut-off wavelength for this surface is (1999)
(a) 3000 Å
(b) 2062.5 Å
(c) 4125 Å
(d) 6000 Å

56. As the intensity of incident light increases (1999)
(a) kinetic energy of emitted photoelectrons increases
(b) photoelectric current decreases
(c) photoelectric current increases
(d) kinetic energy of emitted photoelectrons decreases

57. In a photo-emissive cell, with exciting wavelength λ, the fastest electron has speed ν. If the exciting

58. Which of the following statement is correct? (1997)
(a) The photocurrent increases with intensity of light
(b) The stopping potential increases with increase of incident light
(c) The current in photocell increases with increasing frequency
(d) The photocurrent is proportional to the applied voltage.

59. The kinetic energy of an electron, which is accelerated in the potential difference of 100 volts, is (1997)
(a) 416.6 cal
(b) 6.636 cal
(c) 1.602 x 10^-17
(d) 1.6 x 10⁴ J.

60. An electron beam has a kinetic energy equal to 100 eV. Find its wavelength associated with a

61. In a discharge tube at 0.02 mm, there is formation of (1996)
(a) Crooke’s dark space
(b) Faraday’s dark space
(c) both space partly
(d) none of these.

62. An electron of mass m and charge e is accelerated from rest through a potential difference V in vacuum. Its final velocity will be (1996)

63. If a photon has velocity c and frequency υ), then which of the following represents its wavelength? (1996)

64. The velocity of photons is proportional to (where υ = frequency) (1996)
(a) 1 /√υ
(b) υ
(c) υ
(d) √υ

65. An electron of mass m, when accelerated through a potential difference V, has de Broglie wavelength λ. The de Broglie wavelength associated with a proton of mass M accelerated through the same potential difference, will be (1995)

66. If we consider electrons and photons of same wavelength, then they will have same (1995)
(a) momentum
(b) angular momentum
(c) energy
(d) velocity.

67. When light of wavelength 300 nm (nanometer) falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, however, light of 600 nm wavelength is sufficient for creating photoemission. What is the ratio of the work functions of the two emitters? (1993)
(a) 1 : 2
(b) 2 : 1
(c) 4 : 1
(d) 1 : 4

68. Number of ejected photoelectrons increases with increase (1993)
(a) in intensity of light
(b) in wavelegth of light
(c) in frequency of light
(d) never

69. Momentum of photon wavelength λ is (1993)

70. The cathode of a photoelectric cell is changed such that the work function changes from

71. Photoelectric work function of a metal is 1 eV. Light of wavelength λ = 3000 Å falls on it. The photo electrons come out with a maximum velocity (1991)
(a) 10 metres/sec
(b) 10² metres/ sec j
(c) 10⁴ metres/sec
(d) 10⁶ metres/sec 1

72. The wavelength of a 1 keV photon is 1.24 x 10 9 m. What is the frequency of 1 MeV photon? (1991)
(a) 1.24 x 10¹⁵
(b) 2.4 x 10²⁰
(c) 1.24 x 10¹⁸
(d) 2.4 x 10²³

73. An electron with (rest mass m₀) moves with a speed of 0.8 c. Its mass when it moves with this speed is (1991)

74. A radio transmitter operates at a frequency 880 kHz and a power of 10 kW. The number of photons emitted per second is (1990)
(a) 1.72 x 10³¹
(b) 1.327 x 10²⁵
(c) 1.327 x 10³⁷
(d) 1.327 x 10⁴⁵

75. The momentum of a photon of an electromagnetic

76. Ultraviolet radiations of 6.2 eV falls on an aluminium surface. Kinetic energy of fastest electron emitted is (work function = 4.2 eV) (1989)
(a) 3.2 x 10^-21J
(b) 3.2 x 10^-19J
(c) 7 x 10^-25 J
(d) 9 x 10^-32 J

77. The de Broglie wave corresponding to a particle of mass m and velocity ν has a wavelength associated with it (1989)