For the science fiction novel with the same name, see Incandescence (novel)

Incandescence is the emission of light (visible electromagnetic radiation) from a hot body due to its temperature. The term derives from the verb incandesce, to glow white.

The incandescence of a theoretically perfectly black object is known as black body radiation, which is described by relatively simple mathematical equations. For a black body, the distribution of energy emissions across the electromagnetic spectrum is described by Planck's law. The total power emitted by radiation from a black body is given by the Stefan–Boltzmann law. Wien's displacement law predicts the wavelength of peak emission.

Incandescence occurs in incandescent light bulbs, because the filament resists the flow of electrons. This resistance heats the filament to a temperature where part of the radiation falls in the visible spectrum. The majority of radiation, however, is emitted in the invisible infrared part of the spectrum, which is why incandescent light bulbs are inefficient.

Fluorescent lamps do not function by means of incandescence, rather by a combination of thermionic emission and atomic excitation due to collision with high energy electrons. In an incandescent lamp, only the electrons at the top of the band can participate. While higher temperatures can increase efficiency, there are currently no materials able to withstand such temperatures which would be appropriate for use in fluorescent lamps.

See also

• Incandescent light bulb
• List of light sources

References