What is a Photon?
In physics, a photon is a beam of electromagnetic energy. It is the basic unit that makes up all light. Photons are sometimes called the “quantum” of electromagnetic energy.
Photons are not thought to be composed of smaller particles. They are a fundamental unit of nature called the elementary particle.
Properties of a Photon
Photons have fundamental properties that help define what they are and how they work. These attributes include:
They have zero mass.
They have no electrical charge.
They are stable. They carry energy and momentum that depend on frequency.
They can interact with other particles such as electrons.
They can be destroyed or created by many natural processes.
In a vacuum, they travel at the speed of light.
Photons Interact with Matter
Photons behave like particles in that they can interact with matter. In some cases, photon energy is absorbed by matter. In this case, additional energy can be released as heat. An example of this is asphalt that heats up in the sun.
Our eyes also interact with photons. When a photon hits the eye, it is converted into electrical energy, which is then transmitted to the brain to form an image.
Planck’s Constant
The relationship between the energy of a photon and its frequency can be described by the following equation:
E = hv
where E is the energy, v is the frequency and h is the Planck constant. Planck’s constant is always the same (i.e. “constant”) and equals 6.62606957 * 10-34 m2 kg/s.
Interesting Facts about Photons
Not only is light made up of photons, but all electromagnetic energy (i.e. microwaves, radio waves, X-rays) is made up of photons.
The original concept of photons was developed by Albert Einstein. However, it was scientist Gilbert N. Lewis who first used the word “photon” to describe it.
The theory that light behaves both as a wave and as a particle is called wave-particle duality theory.
Photons are always electrically neutral. They have no electrical charge.
Photons do not decay by themselves.