Quantum Model of Electromagnetic Radiation:

The wave model of electromagnetic radiation described above was successful in explaining a number of observed phenomena thus; it fails to account for the absorption, emission and scattering of radiant energy, discussed in Sec 1.3 and 1.4. It is so since while an electromagnetic radiation is absorbed or emitted, there is a permanent transfer of energy which goes against the extremely concept of wave nature of energy. Therefore a new model for the electromagnetic radiation was required. This is known as the quantum model. The quantum model (also called particle model) of radiation was necessitated by the experimental observations in case of black body radiation and the photoelectric effect. Let us briefly recall these.