### Planck constant

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

The **Planck constant** (**h**) is
6.626068 × 10^{-34} m^{2} 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 **ℏ**) 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.

t_{P} ≡ √(ℏG/c^{5})
m_{P} ≡ √(ℏc/G)
l_{P} ≡ √(ℏG/c^{3})

- t
_{P} - Planck time (5.39 × 10^{-44} s).
- m
_{P} - Planck mass (2.18 × 10^{-5} g).
- l
_{P} - Planck length (1.62 × 10^{-33} cm).
- G - gravitational constant.
- c - speed of light.

(*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

Planck function

Saha equation

Stefan-Boltzmann constant (σ)

Wien's displacement law

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