The energy of a photon of green light of wavelength 5000 Å is

3.459 × 10^–19 joule
3.973 × 10^–19 joule
4.132 × 10^–19 joule
8453 × 10^–19 joule

Solution

An electron is accelerated by a p.d. of 1000 V. Its velocity will be

3.78 × 10⁷m/s
1.89 × 10⁷m/s
5.67 × 10⁷m/s
0.95 × 10⁷m/s

Solution

A photoelectric cell is a device which

converts light into electricity
converts electricity into light
stores light
stores electricity

A photo sensitive metal is not emitting photo-electrons when irradiated. It will do so when threshold is crossed. To cross the threshold we need to increase

intensity
frequency
wavelength
None of these

The momentum of a photon of wavelength λ is

hλ
h/λ
λ/h
h/cλ

Photoelectric effect is the phenomenon in which

photons come out of a metal when it is hit by a beam of electrons.
photons come out of the nucleus of an atom under the action of an electric field.
electrons come out of a metal with a constant velocity which depends on the frequency and intensity of incident light wave.
electons come out of a metal with different velocities not greater than a certain value which depends only on the frequency of the incident light wave and not on its intensity.

The kinetic energy of electron (in electron volt) moving with a velocity of 4 × 10⁶m/s will be

60 eV
50 eV
30 eV
45.5 eV

The de-Broglie wave length of an electron moving in the nth Bohr orbit of radius r is given by

\(\frac{2\pi r}{n}\)
nπr
\(\frac{nr}{2\pi }\)
\(\frac{nr}{\pi }\)

In Davison-Germer experiment, an electron beam is incidenton a crystal. The reflected beam consists of

photons
protons
x-rays
electrons

In which of the following, emission of electrons does not take place?

Thermionic emission
X-rays emission
Photoelectric emission
Secondary emission

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