A photon is an elementary particle, the quantum of light and all other forms of electromagnetic radiation. It is the force carrier for the electromagnetic force, even when static via virtual photons. Photons are emitted in many natural processes.
In empty space, the photon moves at c (the speed of light) and its energy and momentum are related by E = pc, where p is the magnitude of the momentum vector p. Since p points in the direction of the photon’s propagation, the magnitude of the momentum is related to the frequency of the light and the speed of light.
|p||momentum of the photon (kg*m/s)|
|f||frequency of the light (s-1)|
|c||Speed of light|