Plancks Quantum Theory
When black body is heated, it emits thermal radiations of different wavelengths or frequency. To explain these radiations, max planck put forward a theory known as planck’s quantum theory.
(i) The radiant energy which is emitted or absorbed by the black body is not continuous but discontinuous in the form of small discrete packets of energy, each such packet of energy is called a 'quantum'. In case of light, the quantum of energy is called a 'photon'.
(ii) The energy of each quantum is directly proportional to the frequency (v) of the radiation, i.e. E ∞ V or E hv = hc/λ
Where, λ Planck's constant = 6.62×10–27 erg. sec. or 6.62×10-24 joulessec
(iii) The total amount of energy emitted or absorbed by a body will be some whole number quanta. Hence E = nhv where n is an integer.