Science, Tech, Math Science Photon Definition Share Flipboard Email Print A photon is a packet of light or electromagnetic radiation. picturegarden / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry in Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate by Anne Marie Helmenstine, Ph.D. Updated July 24, 2017 Photon Definition: A photon is a discrete packet of energy associated with electromagnetic radiation (light). A photon has energy E which is proportional to the frequency ν of the radiation: E = hν, where h is Planck's constant.Also Known As: quantum, quanta citecite this article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "Photon Definition." ThoughtCo, Jul. 24, 2017, thoughtco.com/definition-of-photon-605908. Helmenstine, Anne Marie, Ph.D. (2017, July 24). Photon Definition. Retrieved from https://www.thoughtco.com/definition-of-photon-605908 Helmenstine, Anne Marie, Ph.D. "Photon Definition." ThoughtCo. https://www.thoughtco.com/definition-of-photon-605908 (accessed April 24, 2018). copy citation Continue Reading