Thermal voltage
The Boltzmann constant (kB or k), which is named after Ludwig Boltzmann, is a physical constant relating the average kinetic energy of particles in a gas with the temperature of the gas. It is the gas constant R divided by the Avogadro constant NA:
The Boltzmann constant has the dimension energy divided by temperature, the same as entropy. As of 2017, its value in SI units is a measured quantity. The recommended value (as of 2015, with standard uncertainty in brackets) is 1.38064852(79)×10−23 J/K.
Current measurements of the Boltzmann constant depend on the definition of the kelvin in terms of the triple point of water. In the proposed redefinition of SI base units scheduled for adoption at the 26th General Conference on Weights and Measures (CGPM) on 16 November 2018, the definition of the kelvin will be changed to one based on a fixed, exact numerical value of the Boltzmann constant, similar to the way that the speed of light was given an exact numerical value at the 17th CGPM in 1983. The final value is not yet known, but will be based on the best measurements published by 1 July 2017.
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