Sep 15 2014
The term photon was coined by Gilbert Lewis in 1926. A photon is a type of elementary particle that forms the basic unit of electromagnetic radiation, which includes infrared, ultraviolet, visible light, X-rays, radio waves, and gamma rays.
The photon is considered as the fundamental particle of light, and is the most visible portion of the electromagnetic spectrum. It has also been described as both a particle and a wave, thereby allowing photons properties such as refraction and diffusion.
Photons in x-rays or ultraviolet rays have short wavelengths and as a result contain more energy. If the wavelengths are longer like in radio waves, then these photons will have less energy.
Photons were crucial components in the discovery of quantum physics. The studying of photons’ properties led to the discovery of a new class of fundamental particles called quantum particles.
The key properties of photons are listed below:
- Move at a constant velocity, i.e., the speed of light in free space
- Stable and have zero mass and rest energy
- Can carry energy and momentum, which are dependent on the frequency
- Can be destroyed/created when radiation is absorbed/emitted
- Can have particle-like interactions with electrons and other particles
- Do not decay unexpectedly in empty space as they do not have any smaller sub particles
Photons have numerous applications in industry and technology. The study of photons aided the invention of charge- coupled devices and chips used within digital cameras. Photons also were key in Einstein’s theory of relativity, and in Planck's energy formula , which is widely used by engineers and chemists in design. Geiger counters use photons to spot radiation due to their ability to identify ionized gas molecules. It is also widely used in molecular biology.
Sources and Further Reading