Some phenomanon of light like as Black body radiation, Photo electric effect, Line spectrum of molecules, Compton effect, Romon effect etc could not be explained on the wave theory. In 1900 Max Plunck proposed quantum theory of light. According to this theory radiation (light) is the sum of many discontinuous small unit and this small unit called Quanta. The energy of a Quanta is E = hν; ν = frequncy of quanta, js.j/sec. Quantum theory could not be explain Interferance and diffraction phenomanon of light.