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Boltzmann constant: The Boltzmann constant, k, is one of seven fixed constants defining the International System of Units, the SI, with k = 1.380 649 x 10 −23 J K −1. The Boltzmann constant is a proportionality constant between the quantities temperature (with unit kelvin) and energy (with unit joule).
kT (also written as k B T) is the product of the Boltzmann constant, k (or k B), and the temperature, T.This product is used in physics as a scale factor for energy values in molecular-scale systems (sometimes it is used as a unit of energy), as the rates and frequencies of many processes and phenomena depend not on their energy alone, but on the ratio of that energy and kT, that is, on E ...
where k B is the Boltzmann constant, S is the classical thermodynamic entropy, and Ω is the number of microstates. So =. Substituting into the definition of β from the statistical definition above gives =.
These include the Boltzmann constant, which gives the correspondence of the dimension temperature to the dimension of energy per degree of freedom, and the Avogadro constant, which gives the correspondence of the dimension of amount of substance with the dimension of count of entities (the latter formally regarded in the SI as being dimensionless).
The proportionality constant k B is one of the fundamental constants of physics and is named the Boltzmann constant in honor of its discoverer. Boltzmann's entropy describes the system when all the accessible microstates are equally likely. It is the configuration corresponding to the maximum of entropy at equilibrium.
The extra constant factor introduced in the denominator was introduced because, unlike the discrete form, the continuous form shown above is not dimensionless. As stated in the previous section, to make it into a dimensionless quantity, we must divide it by h 3 N (where h is usually taken to be the Planck constant).
k B is the Boltzmann constant; T is the absolute temperature. This equation is an early example of a fluctuation-dissipation relation. [7] Note that the equation above describes the classical case and should be modified when quantum effects are relevant. Two frequently used important special forms of the relation are:
where k B is the Boltzmann constant and e is the elementary charge. This empirical law is named after Gustav Wiedemann and Rudolph Franz, who in 1853 reported that κ/σ has approximately the same value for different metals at the same temperature. [2] The proportionality of κ/σ with temperature was discovered by Ludvig Lorenz in 1872. [3]