Planck relation
Energy–frequency relation in quantum mechanics / From Wikipedia, the free encyclopedia
The Planck relation[1][2][3] (referred to as Planck's energy–frequency relation,[4] the Planck–Einstein relation,[5] Planck equation,[6] and Planck formula,[7] though the latter might also refer to Planck's law[8][9]) is a fundamental equation in quantum mechanics which states that the energy E of a photon, known as photon energy, is proportional to its frequency ν:
The constant of proportionality, h, is known as the Planck constant. Several equivalent forms of the relation exist, including in terms of angular frequency ω:
where
. Written using the symbol f for frequency, the relation is
The relation accounts for the quantized nature of light and plays a key role in understanding phenomena such as the photoelectric effect and black-body radiation (where the related Planck postulate can be used to derive Planck's law).