Energy–frequency relation in quantum mechanics
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).
- ^ French & Taylor (1978), pp. 24, 55.
- ^ Cohen-Tannoudji, Diu & Laloë (1973/1977), pp. 10–11.
- ^ Kalckar 1985 harvnb error: no target: CITEREFKalckar1985 (help), p. 39.
- ^ Schwinger (2001), p. 203.
- ^ Landsberg (1978), p. 199.
- ^ Landé (1951), p. 12.
- ^ Griffiths, D. J. (1995), pp. 143, 216.
- ^ Griffiths, D. J. (1995), pp. 217, 312.
- ^ Weinberg (2013), pp. 24, 28, 31.