Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025
Definition
A photon is a quantum of electromagnetic radiation, essentially a particle of light. It has no mass, carries energy, and travels at the speed of light in a vacuum.
The range of all types of electromagnetic radiation including gamma rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves, and radio waves.