Encyclopedia Article

Light - Research Article from World of Biology

This encyclopedia article consists of approximately 1 page of information about Light.
This section contains 160 words
(approx. 1 page at 300 words per page)

Light, also known as visible radiation, is electromagnetic radiation within the wavelength band that can be perceived by the human eye. This range is from about 380-780 nanometers (or nm; 1 nm = 10-9 m). Wavelengths shorter than the lower end of the visible range are known as ultraviolet, and longer ones are infrared.

The electromagnetic spectrum of visible radiation is commonly partitioned into a number of sub-ranges, which correspond to the "colors of the rainbow": red, orange, yellow, green, blue, and violet. These colors have the following wavelength ranges: red, 740-620 nm; orange, 620-585 nm; yellow, 585-575 nm; green, 575-500 nm; blue, 490-445 nm; violet, 445-390 nm.

Sometimes, the word "light" is also used in reference to the entire electromagnetic spectrum, or to components such as gamma, X-ray, ultraviolet, infrared, microwave, or radio. In the physical sense, however, this is an inappropriate use of the word light, which should be restricted to wavelengths in the range of 380 to 780 nm.

This section contains 160 words
(approx. 1 page at 300 words per page)
Light from Gale. ©2005-2006 Thomson Gale, a part of the Thomson Corporation. All rights reserved.
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