Boltzmann constant
J/K
The bridge between temperature and energy: it converts kelvins into joules per particle. It appears everywhere thermal physics meets the microscopic world, from gas laws to entropy. It is exact by SI definition and now anchors the definition of the kelvin.
Used in
- Ideal gas law per particle: pV = NkT
- Entropy S = k log W
- Defining the kelvin
Source: SI defining constants / CODATA 2018