# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Astro*Dictionary by Michael Erlewine





2 articles for "Wavelength"

Wavelength [Astro*Index]

Distance required for a periodic wave to make one complete cycle of oscillation; thus, the distance travelled during one period of oscillation. Wavelength is measured in meters, or fractions thereof. The visible spectrum runs from about 400 to about 800 nanometers.

See also:
♦ Light Spectrum
Wavelength [DeVore]

Radio waves may be measured either in length or in frequency: the higher the frequency, the shorter the length of the waves. For example, your WMCA, at the top of the dial, has a frequency of 570 kilocycles, in a wave that has a length of approximately 527 metres. Multiply one by the other and you have about 300,000. WQXR, near the bottom, has a frequency of 156o kc., and a wave length of approximately 192 metres. These multiplied yield also approximately 300,000-thereby showing a definite inverse ratio between frequency and length of wave. The ultra-short wave lengths in the light band are measured in millimicrons, or angstrom units. A micron is a millionth part of a metre; a millimicron, a thousandth part of a micron; an angstrom, one-tenth of a millimicron. Red light has a wave length of about 780 M M or 7800 A (angstrom units); yellow, 590 M M Or 5goo A; and violet, 390 M M or 3goo A. The range of visibility is thus one octave: from approximately 400 M M to 8oo M M. Above that are the ultra-violet rays, and below it, the infra-red. It is also discovered that refraction increases in inverse ratio to the wave length — hence the dispersion of light as it passes through a glass prism. It is a matter of wave length that Mars yields a red light, stimulates the adrenal glands, and thus produces the sundry emotional reactions that astrologists have learned to associate with a Mars accent: and similarly with all the other planetary rays, as distinguished from those of the luminaries.

See also:
♦ Astronomy ♦ Angstrom


Astro*Index Copyright © 1997 Michael Erlewine