CBSE Class 11-science Answered

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 continuously but discontinuously 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=hv   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=nhv , where n is an integer such as 1, 2, 3, ....

Since, the frequency, wavelength λ, and speed of light c are related by λν = c, the Planck relation for a photon can also be expressed as

The above equation leads to another relationship involving the Planck constant.