What is a photon?

A photon is a fundamental particle of light that carries electromagnetic radiation. It has no mass and travels at the speed of light. Photons are the basic unit of all light and electromagnetic radiation, and they exhibit both wave-like and particle-like properties.

A photon is an elementary particle that is the quantum of light and all other forms of electromagnetic radiation. It is the force carrier for the electromagnetic force. Photons are massless, and travel at the speed of light. They have zero electric charge, and are not affected by magnetic fields.

Photons were first proposed by Albert Einstein in 1905, in his paper on the photoelectric effect. In this paper, Einstein showed that the energy of a photon is proportional to the frequency of the light, and that photons can only be absorbed or emitted in discrete packets of energy. This work earned Einstein the Nobel Prize in Physics in 1921.

Photons are now known to be the fundamental particles of light and all other forms of electromagnetic radiation. They are responsible for the properties of light, such as its speed, wavelength, and frequency. Photons are also involved in a wide variety of physical processes, such as the photoelectric effect, the Compton effect, and the pair production process.