photon
nounUK /ˈfəʊ.tɒn/
US /ˈfoʊ.tɑːn/
A photon is a tiny packet of light.
When you turn on a lamp, it sends out many photons.
OTHER MEANINGS
2. A unit of electromagnetic radiation used in physics to describe light and other forms of energy.
Scientists measured the photon's energy to understand the light's color.
3. In quantum mechanics, the basic particle that carries the electromagnetic force.
Photons carry the electromagnetic force between charged particles.
4. A particle of light that can behave like a wave in some experiments.
The double-slit experiment shows that a photon can act like a wave.