Question

What is a photoelectric effect? Write any three laws of the photoelectric effect. Explain these laws by Einstein's equation of the photoelectric effect.

Answer 1

The photoelectric effect refers to the emission, or ejection of electrons from the surface of a metal in response to incident light. This takes place because of the energy of incident photons of light have energy more than the work potential of the metal surface, ejecting electrons with positive kinetic energy.

Laws of Photo-Electric effect are-

(a) Photoelectric effect is an instantaneous process.

(b) Photoelectric current is directly proportional to the intensity of incident light and is independent of frequency.

(c) The stopping potential and hence the maximum velocity of the electrons depends upon the frequency of incident light and is independent of its intensity.

(d) The emission of electrons stops below a certain minimum frequency known as threshold frequency.

According to Einstein's equation of photoelectric effect,

$E_i=h{\nu }_i=h{\nu }_0+KE$

where $E_i$ is the energy of incident photon, and ${\nu }_0$ is the threshold frequency.