Free Electrons move randomly in a conductor due to attraction of positive charges. So some energy is required to emit electrons from metal surface. Minimum energy is required to emit the electrons on the surface of conductor. This minimum energy …
The Definition of Photo electric effect given in above article. The phenomenon of emission of electrons from a metallic surface by the incidence of light (photons) is known as photoelectric effect. The emitted electrons are called photoelectrons. The below picture …