please explain quantum theory ?

Max Plank in 1901 , gave a new revolutionary theory known as Quantum theory of radiation.

Main features of this theory are :

1. radiant energy is not emitted or absorbed continously but discontinously in the form of small packets of energy called Quanta. Each quanta is associated with a definite amount of energy .
2. E is directly proportional to frequency of light,

         E=h?  where h is known as planks constant.  h= 6.63x10^-34 Js

 

     3.  The total amount of energy emitted or absorbed by the body will be some whole no. multiple of quantum ,i.e,

           E=nh? , where n is an integer such as 1, 2, 3, ....

           we know that     ??=c    so the equation for energy emitted or absorbed becomes

             E=h?/?