18.1 Quantum Theory of Radiation

18.1 Quantum Theory of Radiation

In 1901, Max Planck suggested that energy is radiated or absorbed in discrete packets of energy called quanta rather than as a continuous wave. Quanta is plural of quantum, a discrete packet of energy. Each quantum is associated with radiations of a single frequency. The energy $E$ of each quantum is proportional to its frequency $f$ related as

where $h$ is Planck's constant, its value is $6.63 \times 10^{-34}\,\mathrm{J\,s}$. Max Planck received Nobel Prize in physics in 1918 for his discovery of energy quanta.

For your information

lightbulb

The one important constant $h$ is a constant of quantum theory and another important constant $c$ is the speed of light which is a constant of special theory of relativity.