Physics - Dual Nature of Matter and Radiation

Question - 1

A photon of energy E is incident on a photosensitive substance of work function \(\phi \) such that \(E<\phi \). Consider the two statements
I. Photoelectric effect necessarily takes place
II. The excess energy (in the form of KE) of the emitted electron is exactly \(E-\phi \)

  • A Both (I) and (II) are correct
  • B (I) is correct but not (II)
  • C (II) is correct but not (I)
  • D Both (I) and (II) are incorrect.

Question - 2

The act of photoelectric effect taking place with a certain photosensitive metal depends upon (I) frequency and (II) intensity of the incident radiation.

  • A Both (I) and (II) are correct
  • B Only (I) is correct
  • C Only (II) is correct
  • D Neither (I) nor (II) is correct

Question - 3

Monochromatic light with a frequency well above the cut-off frequency is incident on the emitter in a photoelectric effect apparatus. The frequency of the light is then doubled while the intensity is kept constant. How does this affect the photoelectric current?

  • A The photoelectric current will increase
  • B The photoelectric current will decrease
  • C The photoelectric current will remain the same
  • D None of the above

Question - 4

A point source of light is used in a photoelectric effect. If the source is removed farther from the emitting metal, then the stopping potential.

  • A will increase
  • B will decrease
  • C will remain constant
  • D will either increase or decrease

Question - 5

If the frequency of light in a photoelectric experiment is doubled, then stopping potential will

  • A be doubled
  • B halved
  • C become more than double
  • D become less than double

Question - 6

Let Kbe the maximum kinetic energy of photoelectrons emitted by a light of wavelength \({ \lambda }_{ 1 }\) and K2 corresponding to \({ \lambda }_{ 2 }\). If \({ \lambda }_{ 1 }=2{ \lambda }_{ 2 }\), then

  • A 2K1 = K2
  • B K1 = 2K2
  • C K1 < K2/2
  • D K1 > 2K2

Question - 7

Radiation of two photon energies twice and five times the work function of metal are incident successively on the metal surface. The ratio of the maximum velocity of photoelectrons emitted in the two cases will be

  • A 1 : 2
  • B 2 : 1
  • C 1 : 4
  • D 4 : 1

Question - 8

Cut-off potentials for a metal in photoelectric effect for light of wavelength \({ \lambda }_{ 1 },{ \lambda }_{ 2 }\quad and\quad { \lambda }_{ 3 }\) is found to be \({ V }_{ 1 },{ V }_{ 2 }\quad and\quad { V }_{ 3 }\) volt. If  \({ V }_{ 1 },{ V }_{ 2 }\quad and\quad { V }_{ 3 }\) are in arithmetic progression, then \({ \lambda }_{ 1 },{ \lambda }_{ 2 }\quad and\quad { \lambda }_{ 3 }\) will be

  • A arithmetic progression
  • B geometric progression
  • C harmonic progression
  • D None of the above

Question - 9

Photons with energy 5 eV are incident on a cathode C of a photoelectric cell. The maximum energy of the emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is

  • A 3 V
  • B - 3 V
  • C - 1 V
  • D 4 V

Question - 10

In a photoelectric experiment, the collector plate is at 2.0 V with respect to the emitter plate (made of copper \(\phi =4.5eV\)). The emitter is illuminated by a source of monochromatic light of wavelength 200 nm.

  • A The minimum kinetic energy of the photoelectrons reaching the collector is 0
  • B The maximum kinetic energy of the photoelectrons reaching the collector is 3.7 eV
  • C If the polarity of the battery is reversed, then answer to part A will be 0
  • D If the polarity of the battery is reversed, then answer to part B will be 1.7 eV
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