Photon

A photon is the quantum of electromagnetic radiation, carrying energy and momentum while having zero rest mass and electric charge. Photons are the force carriers of the electromagnetic interaction.

Planck relation: The equation relating a photon's energy to its frequency: energy equals Planck's constant times frequency. It quantifies how photon energy changes with electromagnetic frequency.
Quantum field theory: A framework describing particles as excitations of quantum fields. In this framework, a photon is an excitation of the electromagnetic field.
Black-body radiation: Electromagnetic radiation emitted by an ideal absorber whose spectrum depends on temperature. Its spectrum prompted Planck's introduction of energy quantization.
Laser: A device that produces coherent light through stimulated emission and optical amplification. Lasers generate controlled streams of photons with defined frequencies and phases.
Gluon: A massless gauge boson that mediates the strong interaction and carries color charge. Unlike photons, gluons carry the charge of the force they mediate.
Photon momentum: The momentum carried by a photon, equal to its energy divided by the speed of light. It explains radiation pressure despite photons having zero rest mass.
Electromagnetic field: A physical field comprising electric and magnetic components that interact with charged matter. Photons are quantized excitations of this field.
Max Planck: A German physicist who introduced energy quantization while deriving the black-body radiation law. His 1900 work supplied the quantum idea behind photon energy.
Photodetector: A device that converts incident light into an electrical signal. Photodetectors register photons through processes such as electron generation or charge transfer.
W and Z bosons: Massive elementary particles that mediate the weak interaction. Their nonzero masses distinguish them from the massless photon.

Linked from 121 pages