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refractive index

noun, Optics.
Origin
1830-1840
1830-40
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for refractive index
  • They studied a material with a low refractive index bordered by a layer with a high refractive index.
  • Most optical fibers have a core of pure silica and a cladding layer that is doped with ions to change its refractive index.
  • There's a mismatch between the refractive index of water and air.
  • Each cell type has a unique diffraction signature that depends on its size, shape, and an optical quality called refractive index.
British Dictionary definitions for refractive index

refractive index

noun
1.
(physics) a measure of the extent to which radiation is refracted on passing through the interface between two media. It is the ratio of the sine of the angle of incidence to the sine of the angle of refraction, which can be shown to be equal to the ratio of the phase speed in the first medium to that in the second. In the case of electromagnetic radiation, esp light, it is usual to give values of the absolute refractive index of a medium, that is for radiation entering the medium from free space ν, μ
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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refractive index in Medicine

refractive index n.

Abbr. n The ratio of the speed of light in air or in a vacuum to the speed of light in another medium.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Article for refractive index

index of refraction

measure of the bending of a ray of light when passing from one medium into another. If i is the angle of incidence of a ray in vacuum (angle between the incoming ray and the perpendicular to the surface of a medium, called the normal; see figure), and r is the angle of refraction (angle between the ray in the medium and the normal), the refractive index n is defined as the ratio of the sine of the angle of incidence to the sine of the angle of refraction; i.e., n = sin i / sin r. Refractive index is also equal to the velocity c of light of a given wavelength in empty space divided by its velocity v in a substance, or n = c/v.

Learn more about index of refraction with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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