### Boltzmann constant

**(k, k**_{B})
(relates particle energy and temperature)

The **Boltzmann constant**
(**k** or **k**_{B}) is a
physical constant relating a gas's
mean particle kinetic energy to the gas's temperature.
For particles with no energy tied up in rotation or oscillation,
i.e., single atoms:

mean ke = (3/2)kT

- mean ke - mean kinetic energy of particles in the gas.
- T - temperature.
- k - Boltzmann constant.

The *Boltzmann constant* is the **gas constant**
divided by the **Avogadro constant**.
Its value is 1.380649 × 10^{-16} erg/K.
It is key in statistical mechanics, the relating of statistical
properties of many individual particles to physical characteristics
we perceive at our own scale.

The **Kelvin scale** was re-standardized in 2017 such that this value
of the *Boltzmann constant*
is exact. Given the above formula, any temperature corresponds to
an amount of energy and vice versa, even though in daily life
we perceive them as something different.
The new standard was considered reasonable because careful measures
of the Boltzmann constant under the previous *Kelvin scale*
standard were producing the same value repeatedly and reliably.

(*physics,constant*)
**Further reading:**

http://en.wikipedia.org/wiki/Boltzmann_constant

**Referenced by pages:**

antenna temperature

beta (β)

black-body radiation

Boltzmann equation

electron volt (eV)

ideal gas law

Jeans length

Maxwell-Boltzmann distribution

noise temperature

partition function (Z)

Planck function

Planck units

Rayleigh-Jeans law

Saha equation

Stefan-Boltzmann constant (σ)

temperature

Wien approximation

Index