Encyclopædia Galactica Rami T. F. Rekola Tuorlan Astronomical Society Tuorla Observatory University of Turku

Photon ([gamma])

A quantum of electromagnetic radiation. Electromagnetic radiation shows both wave-like and particle-like properties, and a photon may be considered to be a discrete wave packet. The energy, E, carried by a photon is related to the wavelength, [lambda], of its radiation by the formula

E = h*c/[lambda] = h*[nu]

where h is the Planck's constant, c is the velocity of light, and [nu] is frequency.