When monochromatic radiation of intensity I falls on a metal sur

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81.

An electron in the hydrogen atom jumps from excited state n to the ground state. The wavlength so emitted illuminates a photo -sensitive material having work function 2.75 eV. If the stopping potential of the photo-electron is 10 V, the value of n is 

  • 3

  • 4

  • 5

  • 5

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82.

Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model?

  • 1.9 eV

  • 11.1 eV

  • 13.6 eV

  • 13.6 eV

338 Views

83.

A source S1 is producing, 1015 photons of wavelength 500 A. 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

  • 1.00

  • 1.02

  • 1.04 A

  • 1.04 A

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84.

When monochromatic radiation of intensity I falls on a metal surface, the number of photoelectrons and their maximum kinetic energy and N and T respectively. If the intensity of radiation is 2I, the number of emitted electrons and their maximum kinetic energy are respectively

  • N and 2T

  • 2N and T

  • 2N and 2T

  • 2N and 2T


B.

2N and T

i) Kinetic energy of photoelectrons depends on the frequency of incident radiations and is independent of the intensity of illumination.

ii) A number of photoelectrons depend upon the intensity.

So, the number of emitted electrons and their maximum kinetic energy are 2N and T respectively.

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85.

The mean free path of electrons in a metal is 4 x 10-8 m. The electric field which can give on an average 2 eV energy to an electron in the metal will be in unit of V m-1

  • 8 x 107

  • 5 x 10-11

  • 8 x 10-11

  • 8 x 10-11

1167 Views

86.

The number  of photoelectrons emitted from light of a frequency v (higher than the threshold frequency vo) is proportional to 

  • v-vo

  • threshold frequency (vo)

  • the intensity of light

  • the intensity of light

531 Views

87.

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 second on the average at a target irradiated by this beam is 

  • 9 x 1017

  • 3 x 1016

  • 9 x 1015

  • 9 x 1015

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88.

The figure shows a plot of photocurrent versus anode potential for a photosensitive surface for three different radiations. Which one of the following is a correct statement?


  • Curves a and b represent incident radiations of different frequencies and different intesities

  • Curves a and b represent incident radiations of same frequency but of different intesities

  • Curves b and c represent incident radiations of different frequencies and different intensities

  • Curves b and c represent incident radiations of different frequencies and different intensities

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89.

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 

  • ultraviolet region

  • visible region

  • infrared region

  • infrared region

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90.

The ground state energy of hydrogen atom is -13.6 eV. When its electron is in the first excited state, its excitation energy is

  • 3.4 eV

  • 6.8 eV

  • 10.2 eV

  • zero

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