Light is a form of radiation energy and since the early 20th century physicists have tended to agree that light has a dual nature; it displays the characteristics of both wave and particle phenomena. Light is produced through the energy released in photons. What we perceive as light optically is only a small part of a continuum of radiation energy known as the electromagnetic spectrum.
Every atom is orbited by electrons. When those electrons bounce in and out of different levels of orbit, they emit energy. That can occur, for example, when a substance is heated. The energy that is released is called radiation energy. Since it has electrical and magnetic properties, it is called electromagnetic radiation and the spectrum includes radio waves, microwaves, infrared rays, optical light, ultraviolet rays, X-rays, gamma rays and more.
- Energy is emitted at specific wavelengths.
- The human eye can detect a specific range of wavelengths – optical light.
- Photons are the particle characteristics of light.
- The speed that photons travel is what is known as the speed of light.
- Light is the only wave that can travel through a vacuum.
- In a vacuum, the speed of light is 186,282 miles per second.
Differing levels of energy at the level of the photon and differing wave lengths produce the different types of radiation that make up the electromagnetic spectrum.