Kirchhoff's radiation law
  • A law stating that, for a given temperature and wavelength, the ratio of the emissivity to the absorptivity is the same for all bodies, and is equal to the emissivity of a blackbody at said temperature and wavelength. That is, if a body is a good absorber of a given wavelength at a given temperature, then it will also be a good emitter of said wavelength at that same temperature. And, if a body is at poor absorber of a given wavelength at a given temperature, then it will also be a poor emitter of said wavelength at that same temperature. Also called Kirchhoff's law (3).

Not what you were looking for?