Photo Electric Effect

Description:

When light of sufficient energy (energy more than work function) is incident on a metal plate its electrons are ejected out and can form Electric Current.

This phenomenon is called Photo - Electric effect.

It is commonly used in glass tubes filled with gas. As gas is a bad conductor of electricity, current does not flow in gas but when light or any other radiation is incident on the gas it starts to conduct electric current through it due to photo electric effect.