Quantum ideas starts developing from the failure to explain the spectral distribution of black body radiation. Existing theories at that time e.g. the e.m. theory of the light (wave theory) could not explain the observed spectral distribution (energy distribution) of the black body. Wiens and R.J gave good proposal to explain the
energy distribution curve but both the theories did not t well for the whole spectral wavelength. Max Plank in the year 1900 put a revolutionary concept that the energy of the Black body radiation is quantized.