wave number

noun
the number of waves in one centimeter of light in a given wavelength; the reciprocal of the wavelength.

Origin:
1900–05

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Collins
World English Dictionary
wave number
 
n
physics ν, σ the reciprocal of the wavelength of a wave

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Science Dictionary
wave number  
The number of wave cycles per unit distance for a wave of a given wavelength.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica
Encyclopedia

wave number

a unit of frequency in atomic, molecular, and nuclear spectroscopy equal to the true frequency divided by the speed of light and thus equal to the number of waves in a unit distance. The frequency, symbolized by the Greek letter nu (nu), of any wave equals the speed of light, c, divided by the wavelength lambda: thus nu = c/lambda. A typical spectral line in the visible region of the spectrum has a wavelength of 5.8 10-5 cm; this wavelength corresponds to a frequency (nu) of 5.17 1014 Hz (hertz equals one cycle per second) obtained from the equation. Because this frequency and others like it are so extremely large, it is convenient to divide the number by the speed of light and hence reduce its size. Frequency divided by the speed of light is nu/c, which from the above equation is 1/lambda. When wavelength is measured in metres, 1/lambda represents the number of waves of the wave train to be found in a length of one metre or, if measured in centimetres, the number in one centimetre. This number is called the wave number of the spectrum line. Wave numbers are usually measured in units of reciprocal metres (1/m, or m-1) and reciprocal centimetres (1/cm, or cm-1).

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
Thus, the wave number of minimum brightness temperature should be related to the height of the tropopause.
Wave number two began in the late afternoon and continued into the early evening hours.
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