reciprocal megakelvin

(MK^-1)

   a unit used in colorimetry and photography to measure the wavelength of light, especially for selecting filters to adjust the "color temperature." Light waves of a specific wavelength w meters can be assigned a temperature T using the theory of blackbody radiation. A blackbody is an ideal object that absorbs all the radiation it receives. If a blackbody is heated to temperature T, the radiation it gives off will have maximum intensity at wavelength w, where w and T are related by Wien's law, wT = 2.90 x 10^-3 meter kelvins. The reciprocal of temperature, 1/T = w/(2.90 x 10^-3) K^-1, is thus a measure of wavelength. The wavelengths of visible light fall in the range 400 nanometers (extreme violet) to 700 nanometers (extreme red), corresponding to reciprocal temperatures in the range from roughly 130 MK^-1 to 240 MK^-1. The reciprocal megakelvin has also been called the mired.