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photon definition

☆ pho·ton (fō′tän′)

noun

  1. Particle Physics a subatomic particle, having energy and momentum but no mass or electric charge, that is the quantum unit of electromagnetic radiation, including light
  2. a unit of retinal illumination equal to the illumination from a surface having a brightness of one candle per sq meter seen through a pupil area of one sq millimeter

Etymology: phot(o)- + (electr)on

Related Forms:

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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