Astrophysics (Index)About

Planck constant

(h, Planck's constant)
(quantum of action in quantum mechanics)

The Planck constant (h) is 6.626068 × 10-34 m2 kg/s. The relation of a photon's energy (E) to frequency (F) is:

E = h × f

The reduced Planck constant (aka Dirac constant, abbreviated ) is h/2π, which is convenient because many equations incorporate this expression. A set of units based upon the Planck constant and other fundamental units (Planck units) are fully based upon physical constants, i.e., a type of natural units. Planck units reflect some minimal scales regarding the regime of current physical laws: Planck length, Planck mass, and Planck time. For example, a black hole of the Planck mass (a Planck hole) is considered as small as they can be.

tP ≡ √(ℏG/c5)

mP ≡ √(ℏc/G)

lP ≡ √(ℏG/c3)

(physics,constant,quantum mechanics)
Further reading:
http://en.wikipedia.org/wiki/Planck_constant
http://en.wikipedia.org/wiki/Planck_units

Referenced by pages:
black-body radiation
Bohr model
carbon monoxide (CO)
Compton wavelength
de Broglie wavelength
frequency
kelvin (K)
mass
photon energy
Planck function
Saha equation
Stefan-Boltzmann constant (σ)
Heisenberg uncertainty principle
Wien approximation
Wien's displacement law

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