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photon
photon , the particle composing light and other forms of electromagnetic radiation , sometimes called light quantum. The photon has no charge and no mass. About the beginning of the 20th cent., the classical theory that light is emitted and absorbed by matter in a continuous stream came under criticism because it led to incorrect predictions about several effects, notably the radiation of light by incandescent bodies (see black body ) and the photoelectric effect . These effects can be explained only by assuming that the energy is transferred in discrete packets, or photons, the energy of each photon being equal to the frequency of the light multiplied by Planck's constant, h. Because the value of Planck's constant is extremely small (6.62 × 10 -27 erg sec.), the discrete nature of light energy is not evident in most optical phenomena. The light imparts energy and momentum to a charged particle when one of the photons collides with it, as is demonstrated by the Compton effect . See quantum theory . |
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"photon." The Columbia Encyclopedia, 6th ed.. 2008. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "photon." The Columbia Encyclopedia, 6th ed.. 2008. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1E1-photon.html "photon." The Columbia Encyclopedia, 6th ed.. 2008. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-photon.html |
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photon
photon Quantum of electromagnetic radiation, such as light; a ‘particle’ of light. The energy of a photon equals the frequency of the radiation multiplied by Planck's constant. Absorption of photons by atoms and molecules can cause excitation or ionization. A photon may be classified as a stable elementary particle of zero rest mass, zero charge, spin 1, and travelling at the velocity of light. It is its own antiparticle. Virtual photons are thought to be continuously exchanged between charged particles and thus to be the carriers of electromagnetic force (potential difference between terminals in a source of electric current). See also quantum theory
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"photon." World Encyclopedia. 2005. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "photon." World Encyclopedia. 2005. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O142-photon.html "photon." World Encyclopedia. 2005. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-photon.html |
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photon
photon A particle of electromagnetic radiation. A photon has zero rest mass, zero charge, and travels at the speed of light. The energy, E, of a photon is related to its frequency, f, by the formula E = hf, where h is the Planck constant. Hence a photon at a radio frequency is of much lower energy than a gamma-ray photon.
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"photon." A Dictionary of Astronomy. 1997. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "photon." A Dictionary of Astronomy. 1997. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O80-photon.html "photon." A Dictionary of Astronomy. 1997. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-photon.html |
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photon
pho·ton / ˈfōtän/ • n. Physics a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass. |
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"photon." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "photon." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O999-photon.html "photon." The Oxford Pocket Dictionary of Current English. 2009. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-photon.html |
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photon
photon •Agamemnon, Memnon
•ninon, xenon
•noumenon • Trianon • xoanon
•organon • Simenon • Maintenon
•crampon, kampong, tampon
•Nippon • coupon
•Akron, Dacron, macron
•electron • natron • Hebron • positron
•Heilbronn • micron
•boron, moron, oxymoron
•neutron • interferon
•fleuron, Huron, neuron
•Oberon • mellotron • aileron
•cyclotron • Percheron • Mitterrand
•vigneron • croissant • Maupassant
•garçon • Cartier-Bresson • exon
•frisson • Oxon • chanson • Tucson
•soupçon • Aubusson • Besançon
•penchant • torchon • cabochon
•Anton, canton, Danton
•lepton
•piton, Teton
•krypton • feuilleton • magneton
•chiton
•photon, proton
•croûton, futon
•eschaton • peloton • contretemps
•telethon
•talkathon, walkathon
•Avon • tableau vivant • vol-au-vent
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Cite this article
"photon." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "photon." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O233-photon.html "photon." Oxford Dictionary of Rhymes. 2007. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-photon.html |
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