Also found in: Dictionary, Wikipedia.
Stefan's law(steff -ănz) (Stefan-Boltzmann law) The law relating the total energy, E , emitted over all wavelengths, per second, per unit area of a black body, with the temperature, T , of the body:
σ is Stefan's constant, which has the value 5.6705 × 10–8 W m–2 K–4. The law can be derived from Planck's radiation law (see black body), but was first deduced by Josef Stefan in 1879 and then derived from thermodynamics by Ludwig Boltzmann in 1884. See also luminosity.