Scientists Say: Photon

This particle represents a little packet of light

Lasers, like the one this researcher is using, create a beam of photons. The photons in a laser all have the same energy. Lasers can be used for all sorts of things, from studying chemical reactions as they happen to reading the information on a DVD to play a movie.

Михаил Руденко/iStock/Getty Images Plus

Photon (noun, “FOH-TAHN”)

This word describes a particle of light. A photon is a unit of light that cannot be broken into smaller pieces. This particle is the tiniest possible packet of electromagnetic radiation.

Light’s motion is often described as a wave. But light also has some properties of a particle. One of those properties is that photons can be counted, like beads on a string.

Photons can have different energies. A photon of visible light, such as light that’s the color blue, has a lower energy than an X-ray photon. Scientists can use beams of high-energy X-ray photons to study the properties of matter and molecules.

In a sentence

Human eyes are sensitive enough to see a single photon.

Check out the full list of Scientists Say.

Carolyn Wilke is a former staff writer at Science News for Students. She has a Ph.D. in environmental engineering. Carolyn enjoys writing about chemistry, microbes and the environment. She also loves playing with her cat.

More Stories from Science News for Students on Physics