Compton   effect      In   the   quantum   interpretation  of electromagnetic radiation (light, X rays, g rays) is visualized as bundles  of  energy, which are called photons. The scattering of electromagnetic  radiation  from  free electrons that results in the scattered  radiation  having  frequency  smaller  than  the incident radiation   can   be explained   using  the  quantum interpretation  of electromagnetic radiation. The scattering can be viewed as collision of the photon and  the  charged  particle,  where conservation  of  energy and momentum  can be applied. It leads to the result that the change in the wavelength D l , is given by,

D l = [h/(m₀ c) ] (1- cos q )

where  h is the  Planck's  constant*,  m_o the rest mass of the charged particle, c the velocity of light and q the angle at which the scattered  photon  is  observed.  h/m_oc  is  usually called the Compton  wavelength of the charged particle. For an electron its value  is 0.0243 A. The shift in the wavelength depends on the scattering  angle q  and is independent  of  the  incident  photon energy.

Compton  derived the result, and therefore the phenomenon is called Compton effect. The effect can be verified using X-rays.