- Also called photon. A particle with no mass nor charge, and which composes light and other forms of electromagnetic radiation. gamma rays and X-rays are examples of higher-energy photons, while infrared rays and radio waves are examples of lower-energy forms. Its energy is equal to hf, where h is the Planck constant, and f is the frequency of the radiation in hertz. Photons are required to explain phenomena such as the photoelectric effect, in which light has particle-like properties. The photon is the carrier of the electromagnetic force, which is the force responsible for all electromagnetic interactions, such as those which hold atoms and molecules together.
Not what you were looking for?