Question

What is the Photoelectric Effect?

Answer 1

Photoelectric effect: The photoelectric effect is the phenomenon in which electrons are ejected from the surface of a metal when a beam of light having sufficient frequency strikes the surface of the metal.

• These ejected electrons are referred to as photoelectrons.
• The energy of the ejected photoelectrons is dependent on the frequency of the incident light and the number of electrons ejected depends on the intensity of light.
• It involves the absorption of energy by electrons (belonging to the atoms present at the surface of the metal) from the incident light and the subsequent usage of this energy to overcome the forces of attraction that keep the electrons bound to the nucleus of the metallic atoms.

Observation:

• Light of any frequency is not able to eject electrons from the metal surface. There is a minimum frequency which is known as threshold frequency which can cause the emission of electrons.
• The increase in the intensity of light does not increase the energy of photoelectrons, merely increases the rate of emission.

Einstein equation of photoelectric effect:

These ‘light particles’ are called photons. The energy possessed by a photon can be related to the frequency of the light with the help of Einstein’s equation which is expressed as

$\mathrm{E}=\mathrm{h\nu }-{\mathrm{h\nu }}_0$

where h is a Planck's constant and its value is$6.63\times {10}^{-34}$, $\mathrm{\nu }$ is Frequency, ${\mathrm{v}}_0$is the Threshold frequency.