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 to frequency is

```E = h × f
```

(E being energy, f being frequency).

The reduced Planck constant (or Dirac constant, abbreviated ) is h/2π, which is convenient because many equations incorporate this expression.

A set of units based upon fundamental constants, including the Planck constant determine some minimal scales regarding 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)
http://en.wikipedia.org/wiki/Planck_constant
http://en.wikipedia.org/wiki/Planck_units

Referenced by:
black-body radiation
Bohr model
carbon monoxide (CO)
de Broglie wavelength
frequency
mass
Planck function
Saha equation
Stefan-Boltzmann constant (σ)
Wien's displacement law

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