What is photoelectric effect? State the result of photoelectric effect experiment that could not be explained on the basis of laws of classical physics. Explain this effect on the basis of quantum theory of electromagnetic radiations.
Photoelectric effect states that when specific metals are exposed to a light beam, the metal ejects the electrons. This phenomenon is known as the photoelectric effect. The electrons ejected are called photoelectrons.
The results of this experiment were:
i) The electrons are ejected from the metal surface only as the beam of light strikes the surface.
ii) The number of electrons is proportional to the intensity of radiation.
iii) For each metal; there is a minimum frequency, below which photoelectric effect is not observed.
iv) K.E. of electrons is proportional to the frequency of light.
When a photon of adequate energy strikes an electron in the atom of the metal, it transfers its energy to the electron, and the electron is expelled without any delay. Greater is the energy of the photon, greater will also be the kinetic energy of the ejected electron.