Last updated on September 25th, 2020 at 02:48 am
What Is A Photon?
|sunshine breaking through clouds|
A photon, the quantum of electromagnetic radiation, is an elementary particle; a bundle of energy. It is a force carrier of an electromagnetic force. Photons are tiny particles of light that are too small to be seen individually. Photons are best explained by Quantum Physics. The modern concept of photon theory was developed by the great Albert Einstein. The name photon was coined by an American physical chemist Gilbert Newton Lewis in 1926. A photon has zero rest mass; is always in motion and moves at the speed of light ( c= 2.998 x 108 m/s). A photon is usually denoted by the symbol Υ (gamma).
Historical Development Of A Photon
|young’s double-slit experiment demonstrating light is a wave phenomenon|
Credit: Wikimedia Commons
Photon Exhibits Wave-Particle Duality
Light as both particle and wave
Physical Properties Of Photons
- Photons are massless particles, has no electric charge, can also behave like both a particle and a wave simultaneously.
- Photons are gauge boson for electromagnetism having all quantum numbers such as baryon number, lepton number, and flavor quantum number mathematically equal to zero.
- photons have zero mass and rest energy; in a vacuum, photons move at speed of light i.e = 2.9979 x 108 m/s.
- A photon can be destroyed or created when radiation is either absorbed or emitted.
- A photon does not obey the Pauli exclusion principle.
- A photon follows Bose-Einstein Statistics; making photon a boson having spin number = 1
- A photon can be emitted in many natural processes such as when a charge is accelerated, it emits Synchrotron Radiation or during Electron-Positron Annihilation.
- The energy and momentum of a photon are related by E = pc; where C = speed of light and P = magnitude of a momentum vector.