An Etymological Dictionary of Astronomy and Astrophysics

For all metals the ratio of the → thermal conductivity, κ, to the → electrical conductivity,
σ, is directly proportional to the absolute temperature: K/σ = (1/3)(πk/e)²T, where k is → Boltzmann’s constant and e the electron’s charge.

See also: Named after the German physicists Gustav Heinrich Wiedemann (1826-1899) and Rudolph Franz (1826-1902); → law.