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MCQ On Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter

(1) According to Einstein’s photoelectric equation, the graph of kinetic energy of the photoelectron emitted from the metal versus the frequency of the incident radiation gives a straight line graph, whose slope
[A] depends on the intensity of the incident radi-ation.
[B] depends on the nature of the metal and also on the intensity of incident radiation.
[C] is same for all metals and independent of the intensity of the incident radiation.
[D] depends on the nature of the metal.
Answer: is same for all metals and independent of the intensity of the incident radiation.
(2) In photoelectric effect, the photoelectric current is independent of
[A] intensity of incident light
[B] potential difference applied between the two electrodes
[C] the nature of emitter material
[D] frequency of incident light
Answer: frequency of incident light

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(3) Which of the following statements is correct regarding the photoelectric experiment?
[A] The photocurrent increases with intensity of light.
[B] Stopping potential increases with increase in intensity of incident light.
[C] The photocurrent increases with increase in frequency.
[D] All of these
Answer: The photocurrent increases with intensity of light.
(4) In photoelectric effect, stopping potential depends on
[A] frequency of incident light
[B] nature of the emitter material
[C] intensity of incident light
[D] both (a) and (b)
Answer: both (a) and (b)
(5) A metal surface ejects electrons when hit by green light but nothing when hit by yellow light. The electrons will be ejected when the surface is hit by
[A] blue light
[B] heat rays
[C] infrared light
[D] red light
Answer: blue light
(6) The maximum value of photoelectric current is called
[A] base current
[B] saturation current
[C] collector current
[D] emitter current
Answer: saturation current
(7) The phenomenon of photoelectric emission was discovered in 1887 by
[A] Albert Einstein
[B] Heinrich Hertz
[C] Wilhelm Hallwachs
[D] Philipp Lenard
Answer: Heinrich Hertz
(8) In photoelectric effect, the photocurrent
[A] depends both on intensity and frequency of the incident light.
[B] does not depend on the frequency of incident light but depends on the intensity of the inci-dent light.
[C] decreases with increase in frequency of inci-dent light.
[D] increases with increase in frequency of inci-dent light.
Answer: does not depend on the frequency of incident light but depends on the intensity of the inci-dent light.
(9) Which phenomenon best supports the theory that matter has a wave nature?
[A] Electron momentum
[B] Electron diffraction
[C] Photon momentum
[D] Photon diffraction
Answer: Electron diffraction
(10) The minimum energy required for the electron emission from the metal surface can be supplied to the free electrons by which of the following physical processes?
[A] Thermionic emission
[B] Field emission
[C] Photoelectric emission
[D] All of these
Answer: All of these
(11) Cathode rays were discovered by
[A] Maxwell Clerk James
[B] Heinrich Hertz
[C] William Crookes
[D] J.J. Thomson
Answer: William Crookes
(12) The figure shows stopping V0A potential V0 and frequency o for two different metallic surfaces A and B. The work function of A, as compared to that of B is

[A] less
[B] more
[C] equal
[D] nothing can be said
Answer: less
(13) Who established that electric charge is quantised?
[A] J.J. Thomson
[B] William Crookes
[C] R.A. Millikan
[D] Wilhelm Rontgen
Answer: R.A. Millikan
(14) What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of 100 volts?
[A] 12.3 Å
[B] 1.23 Å
[C] 0.123 Å
[D] None of these
Answer: 1.23 Å
(15) Compared to liquids and solids, gases are:
[A] good conductors of electricity
[B] best conductors of electricity
[C] very poor conductors of electricity
[D] good or bad conductors of electricity depending upon the nature of the gas
Answer: very poor conductors of electricity
(16) which Characteristic of a target does the Mosley’s law relate the frequency of X-rays?
[A] density
[B] atomic number
[C] atomic weight
[D] interatomic space
Answer: atomic number
(17) The de-Broglie wavelength of particle of mass 1 mg moving with a velocity of 1 ms-1, in terms of Planck’s constant h, is given by (in metre):
[A] 10h
[B] 106 h
[C] 10-3 h
[D] 103 h
Answer: 106 h
(18) Which of the following radiations cannot eject photo electrons?
[A] ultraviolet
[B] infrared
[C] visible
[D] X-rays
Answer: infrared
(19) When a yellow light is incident on a surface, no electrons are emitted while green light can emit electrons. If the red light is incident on the surface then:
[A] no electrons are emitted
[B] photons are emitted
[C] electrons of higher energy are emitted
[D] electrons of lower energy are emitted
Answer: no electrons are emitted
(20) Evidence of the wave nature of light cannot be obtained from:
[A] diffraction
[B] interference
[C] doppler effect
[D] reflection
Answer: reflection

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