Infrared

Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength. Infrared radiation spans three orders of magnitude and has wavelengths between 700 nm and 1 mm.

History

The discovery of infrared radiation is commonly ascribed to William Herschel, the astronomer in the early 19th century. Herschel used a prism to refract light from the sun and detected the infrared, beyond the red part of the spectrum, through an increase in the temperature recorded on a thermometer.

Related Topics:
William Herschel - Astronomer - 19th century - Prism - Refract - Thermometer

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