# Planck’s Quantum Theory

While heating black body, it emits thermal radiations of different wavelengths or frequency. Max Planck put forward a theory to explain these radiations, known as Planck’s quantum theory. The main points of quantum theory are

i) Substances radiate or absorb energy discontinuously in the form of small packets or bundles of energy.

ii) The smallest packet of energy is called quantum. In case of light, the quantum is known as photon.

iii) The energy of a quantum is directly proportional to the frequency of the radiation . E (or) E = h where is the frequency of radiation and h is Planck’s constant having the value 6.626 10–27 erg – sec or 6.626 10–34 J–sec.

iv) A body can radiate or absorb energy in whole number multiples of a quantum h, 2h,3h...........nh. where n is a positive integer.