Photoelectric effect was discovered in 1887 by Heinrich Rudolf Hertz. It refers to the ejection or emission of electrons when light hits a material (generally metal). Emitted electrons are called photo-electrons but the intensity of the light determine the kinetic energy of emitted electron.
Intensity of light is directly proportional to the kinetic energy emitted by an electron, that means more intensity the light have more will be the kinetic energy emitted by an electron.
