The wavelength λ_e of an electron and λ_p of a photon are of same energy E are related by

λ_p α λ_e
λ_p α √λ_e
$\lambda _{p}\alpha \frac{1}{\sqrt{\lambda _{e}}}$
λ_p α $\lambda _{e}^{2}$

Solution

For photoelectric emission from certain metal the cut-off frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)

$\sqrt{hv/m}$
$\sqrt{2hv/m}$
$2\sqrt{hv/m}$
$\sqrt{hv/(2m)}$

Solution

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 materials is

4 × 10¹⁵Hz
5 × 10¹⁵Hz
1.6 × 10¹⁵Hz
2.5 × 10¹⁵ Hz

Solution

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

1.5 × 10²⁰
6 × 10¹⁸
62 × 10²⁰
3 × 10¹⁹

Solution

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

1 : 4
1 : 2
1 : 1
1 : 5

Solution

If the momentum of electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%.The initial momentum of electron will be

200 P
400 P
200 P
100 P

Solution

The threshold frequency fora photosensitive metal is 3.3 × 10¹⁴ Hz. If light of frequency 8.2 ×10¹⁴ Hz is incident on this metal, the cut-off voltage for the photoelectric emission is nearly

Solution

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

1.8 V
1.2 V
0.5 V
2.3 V

Solution

The stopping potential is equal to maximum kinetic energy.

Photoelectric emmision occurs only when the incident light has more than a certain minimum

power
wavelength
intensity
frequency

Solution

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

2.4 V
– 1.2 V
– 2.4 V
1.2 V

Solution

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