By Team Aakash Byju's

The mathematical expression of Einstein’s theory is:

He discovered that when a photon falls on the metal's surface, the entire photon’s energy is transferred to the electron.

This energy is used to remove the electron from the metal and the rest is given to the ejected electron as kinetic energy.

At the threshold frequency, 0, electrons are just ejected and do not have any kinetic energy.

Thus, the maximum kinetic energy that the ejected electrons have can be given by the formula: