Nature of Light
Light is an electromagnetic radiation. Although light is only a tiny part
of the electromagnetic spectrum, it has been the subject of much
research both in physics and in biology. The importance of light is due
to its fundamental role in living systems. The sun is still the major
source of light in the world. The sun is both beneficial and hazardous
to our health.
The three general categories of light ultra-violet (UV), visible and
infrared (IR). They are defined in terms of their wavelengths.
Ultraviolet light has wave lengths from about 1000 to 4000 A0; visible
light extends from about 4000 to 7000 A0 and IR light extends form
about 7000 to 100000 A0.
