CBSE
Multiple Choice QuestionsLight of wavelength 500 nm is incident on metal with work function 2.28 eV. The de - Broglie wavelength of the emitted electrons is
<2.8 x 10-10 m
<2.8 x 10-9 m
> equal to 2.8 x 10-9 m
> equal to 2.8 x 10-9 m
Photoelectric emission occurs only when the incident light has more than a certain minimum
wavelength
intensity
frequency
frequency
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
A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and λ/2. If the maximum kinetic energy of the emitted photoelectrons 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)
hc/ 2λ
hc/λ
2 hc/λ
2 hc/λ
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,
0.65 eV
1.0 eV
1.3 eV
1.3 eV
For photoelectric emission from certain metal, the cut-off frequency is v. If radiation of frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electrons will be (m is the electron mass)
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
1.3 V
0.5 V
2.3 V
2.3 V
In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by
Increasing the filament current
decreasing the filament current
decreasing the potential difference between the anode and filament
decreasing the potential difference between the anode and filament
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,
25
75
60
60
The threshold frequency for a photo-sensitive 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 photo-electric emission is nearly
2 V
3 V
5 V
5 V
