- a quantum of electromagnetic radiation, usually considered as an elementary particle that is its own antiparticle and that has zero rest mass and charge and a spin of one. Symbol: γ
Origin of photon
Also called light quantum.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for photon
When the gamma rays enter the sleeve, they interact with that photon gas, annihilating into electron-positron pairs.We Can Create Matter from Light?!
Matthew R. Francis
May 20, 2014
The medicine worked because the photon–the quantum bundle of light and the carrier of the electromagnetic force–has no mass.Finding Higgs Boson, or God Particle, Will Resolve Scientific Mysteries
December 17, 2011
Among his pastimes was designing a solar-power car, the Photon Torpedo.The Guy Who's Got $700 Billion of Your Money
October 9, 2008
Or, the photon may be retained for a while and emitted again relatively unchanged—the effect observed in luminous paint.
Or there may be an inelastic collision, when the photon hits an atom and knocks out an electron—the old photoelectric effect.
"Well, you know what happens when a photon comes in contact with the atomic structure of matter," Kato said.
There were hundreds of scintillations, each caused by a nuclear particle or photon striking the screen.The Blue Ghost Mystery
Harold Leland Goodwin
- a quantum of electromagnetic radiation, regarded as a particle with zero rest mass and charge, unit spin, and energy equal to the product of the frequency of the radiation and the Planck constant
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for photon
Online Etymology Dictionary, © 2010 Douglas Harper
- The quantum of electromagnetic energy, generally regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- The subatomic particle that carries the electromagnetic force and is the quantum of electromagnetic radiation. The photon has a rest mass of zero, but has measurable momentum, exhibits deflection by a gravitational field, and can exert a force. It has no electric charge, has an indefinitely long lifetime, and is its own antiparticle. See Note at electromagnetic radiation. See Table at subatomic particle.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.