- Incandescence
Incandescence is the emission of
light (visibleelectromagnetic radiation ) from a hot body due to its temperature. [cite book | title = Treatise on Heat
author = Dionysius Lardner | publisher = Longman, Rees, Orme, Brown, Green & Longman | year = 1833 | url = http://books.google.com/books?id=jjYIAAAAIAAJ&pg=PA341&dq=incandescence+becomes-luminous&lr=&as_brr=1&ei=Hyk7SMu8FJHUsgOf28XBCw | quote = The state in which a heated body, naturally incapable of emitting light, becomes luminous, is called a state of "incandescence". ] The term derives from the verb "incandesce," to grow white. [cite book | title = An Introduction to Practical Chemistry, Including Analysis | author = John E. Bowman | edition = Second American edition | publisher = Philadelphia: Blanchard and Lea | year = 1856 | url = http://books.google.com/books?id=ffTcf4FGOx4C&pg=PA283&dq=incandesce+date:0-1860&lr=&as_brr=1&ei=vy07SMLWOYvAsgP3vPHPDA ]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 theelectromagnetic spectrum is described byPlanck's law . The total power emitted by radiation from a black body is given by theStefan–Boltzmann law .Wien's displacement law predicts the wavelength of peak emission.Incandescence occurs in
incandescent light bulb s, 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. [cite book | title = Illumination and Photometry | author = William Elgin Wickenden | publisher = McGraw-Hill | year = 1910 | url = http://books.google.com/books?id=gVZDAAAAIAAJ&pg=PA3&dq=incandescent+low-efficiency+blackbody&lr=&as_brr=1&ei=idBGSJ-RMJGosgPKq42wDQ ]Fluorescent lamp s do not function by means of incandescence, rather by a combination ofthermionic 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. Higher temperature can increase efficiency but we do not have materials that can withstand much higher temperature.See also
*
Incandescent light bulb
*List of light sources References
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