First things first. Before we tap into the
wealth of resources here, we have to go into the basics first. What is light ? Where and
how does it exists ?
Electromagnetic
radiation is the transmission of energy in the form of waves having both an
electric and a magnetic component.
Thus according to the above definition, light
is a form of electromagnetic radiation. All of them consists of what we known as waves.
Some waves which you might find them familiar are radio waves and light waves. Less
familiar forms are infrared radiation, ultraviolet light, X rays, and gamma rays. All of
the above types mentioned will constitute the electromagnetic spectrum.
The electromagnetic
spectrum is the range of electromagnetic waves arranged by its increasing
frequency and wavelength.
By theory, the electromagnetic spectrum
extends from zero, the short wavelength limit of the gamma-ray end of the spectrum, to
infinity, the long wavelength limit of the radio end of the spectrum. The only portion of
the spectrum to evoke the sensitivity of the eye occupies a narrow band from about
3.8/10,000,000 to 7.5/10,000,000 meters. In other words, the eye will not be able to see
any light at any range outside this specific band.
Some sources of radiation are the Sun, a
flame, an electrical discharge or an incandescent solid. However, no one source of
radiation may produce one frequency of electromagnetic wave. What they do is to emit a
mixture of waves of many frequencies in a go.
