(i) A chamber containing black body radiations also contains simple harmonic oscillators of molecular dimensions which can vibrate with all possible frequencies.

(ii) The frequency of radiation emitted by an oscillator is the same as the frequency of its vibration.

(iii) An oscillator cannot emit energy in a continuous manner. It can emit energy in the multiples of a small unit called quantum (photon). If an oscillator is vibrating with a frequency v, it can only radiate in quantas of magnitude hv i.e., the oscillator can have only discrete energy values E_n given by
E_n = n h v
where n is an integer and h is Planck's constant (6.625 x 10^-34 joules-sec).

(iv) The oscillators can emit or absorb radiation energy in packets of hv. This implies that the exchange of energy between radiation and matter cannot take place continuously but are limited to discrete set of values 0, hv, 2hv, 3hv, nhv.


Planck's quantum hypothesis is considered as a radical departure from classical theory, because it considers that the energy of the oscillating particle of atomic dimension is taken as discrete rather than continuous and it helped to explain many physics phenomena of 20th century.

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By :-   Dr. A. W. Pangantiwar