The temperature of a system in classical thermodynamics is intimately related to the zeroth law of thermodynamics; two systems having to have the same temperature if they are to be in thermal equilibrium (i.e. there is no net heat flow between them). However, it is most useful to have a temperature scale. By making use of the ideal gas law one can define an absolute temperature
however, perhaps a better definition of temperature is
where S is the entropy.
It is frequently convenient to define a so-called inverse temperature, β, such that
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