The postulates of Planck’s quantum theory are

The emission of radiation is due to vibrations of charged particles (electrons) in the body.

The emission is not continuous but in discrete packets of energy called “**quanta**”. This emitted radiation propagates in the form of waves.

The energy (E) associated with each quantum for a particular radiation of frequency is given by . Here ‘*h’ is Planck’s constant.*

A body can emit or absorb either one quantum () of energy or some whole number multiple of it. Thus energy can be emitted or absorbed as , 2, 3 etc. But not fractional values. This is called **quantization of energy.**

The emitted radiant energy is propagated in the form of waves.

Value of Planck’s constant in various units: