Please explain what is the Photoelectric effect?

Photoelectric Effect

When light of sufficiently small wavelength is incident on a metal surface, electrons are ejected from the metal. This phenomenon is called photoelectric effect and the electrons ejected are called photoelectrons. An experiment setup was arranged to study photoelectric effect, and the results obtained from the experiment are:

1.     When the light of sufficient small wavelength falls on a metal surface, the metal emits photoelectrons. This emission of photoelectrons is instantaneous.

2.     The photoelectric current i.e., the number of photoelectrons emitted per second depends on the intensity of the incident light.

3.     The maximum kinetic energy with which electrons come out of the metal depends only on frequency of incident light and is independent of intensity light.

4.     There is a threshold wavelength for a given metal such that if the wavelength of the incident light is greater than the threshold, there will be no emission of photoelectrons.