Color Vision

Light & Color

Cosmic Rays	Wavelengths Less Than One Nanometer
Gamma Rays
X-Rays
Ultraviolet
Visible Light	Approx. 360-750 nm
Infrared
Hertzian Rays (Radar)
Radio & Television Rays
Long Electrical Oscillations	Wavelengths Measured in Thousands of Kilometers

Visible light is a form of radiant energy and is part of an overall spectrum of energy called the electromagnetic spectrum. As illustrated above, the scope of the electromagnetic spectrum is enormous. It ranges from extremely short waves such as cosmic rays measuring less than one nanometer (one billionth of a meter) in length, to radio and T.V. waves whose wave lengths measure in the thousands of kilometers. That portion of the electromagnetic spectrum to which the photosensitive receptors of the retina respond lies about in the middle of the spectrum and we call it visible light. As demonstrated above, visible light occupies only a very small portion of the overall spectrum of radiant energy. In optics we are concerned not only with the visible spectrum but also with those wave lengths immediately surrounding it which constitute ultraviolet and infrared radiation or �invisible light.� The chart on the next page amplifies the visual spectrum.