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
photon in American English
(ˈfoʊˌtɑn)
US
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
see also classon
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
Derived forms
photonic (phoˈtonic)
adjective
Word origin
photo- + electron
Examples of 'photon' in a sentence
photon
It is like a dance of starlight, an endless photon stream, always moving, always beautiful, impossible to really see.