Major objective of this assignment is to Discuss on Quantum Theory of Radiation. This discussion of Einstein’s idea of relativity took us in a world far beyond of which of ordinary experience – the entire world of objects moving at speeds nearby the speed of light. Now you might be about to explore another world that is external ordinary experience- the subatomic planet. You will encounter a whole new set of surprise of which, though may sometime seem to be bizarre, have led physicists step by step to a deeper look at of reality. Here explain Theory of Radiation with mathematical and theoretical examples.