# Planck's constant

Planck's constantPhysics a universal constant (

*h*) which gives the ratio of a quantum of radiant energy (*E*) to the frequency (?) of its source: it is expressed by the equation*E*=*h*?, and its approximate numerical value is 6.626 × 10 joule secondoften Planck constant

Origin of Planck's constant

after Planck## Planck's constant

noun

**h**

The constant of proportionality relating the energy of a photon to the frequency of that photon. Its value is approximately 6.626 × 10

^{−34}joule-seconds.Origin of Planck's constant

AfterMax Karl Ernst Ludwig**Planck**

## planck-s-constant

Noun

- (physics) the constant of proportionality (symbol
*h*), relating the energy and frequency of a photon (6.626 x 10^{-34}joule-seconds); also related to the indeterminacy limit in the Heisenberg uncertainty principle; the quantum of action

Origin

Named for Max Planck (1858-1947), German theoretical physicist, who discovered it in 1900.