# Photons

A Photon is a discrete packet of electromagnetic radiation [1]. It is the elementary exchange particle for the electromagnetic force. The Energy of a photon depends on its frequency and is given by the equation:

E = hf

where f is the frequency of the electromagnetic wave and h is Planck's constant and has the numerical value of $6.626\times10^{-34}$Js (Joules times second) or $4.135\times10^{-15}$eV s (electron volts times second).

## References

1. A French, P Taylor.(1978). A Introduction to Quantum Physics. MIT: CRC Press.