sentence: Photons have energy and momentum.
sentences_after: When two electromagnetic fields act on each other, they switch photons. So photons carry the electromagnetic force between charged objects. Photons are also known as messenger particles in physics because these particles often carry messages between objects. If a force exists while time passes, then photons are being exchanged during that time.
concept_name: photon
headings: Electromagnetism Electromagnetic radiation Photons