Radius of an electron is estimated about 2 x 10-10 cm, this radius is assume to be rest radius of electron but when electron absorbed the energy from external sources (photon) the radius of electron goes to increases by +x while emitting the energy the radius of an electron goes to decreases –y. This increasing and decreeing take place because electron is constituent of particles. That mean electron is a single system, which on absorbing the energy the constituent particle goes on vibration and this vibration causes the electron to expand the radius. While in emitting the energy, the constituent particle reduces the vibration and this reduces vibration causes contraction of radius of electron. But the radius of electron which is not goes on energy absorption phenomena they have constant estimate radius about 2x10-10cm. Hence the radius of the electron is also depend upon the energy absorption or amount of energy incidence on electrons