index of refraction

noun Optics.
a number indicating the speed of light in a given medium as either the ratio of the speed of light in a vacuum to that in the given medium (absolute index of refraction) or the ratio of the speed of light in a specified medium to that in the given medium (relative index of refraction) Symbol: n
Also called index, refractive index.


Origin:
1820–30

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World English Dictionary
index of refraction
 
n
another name for refractive index

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Science Dictionary
index of refraction  
A measure of the extent to which a substance slows down light waves passing through it. The index of refraction of a substance is equal to the ratio of the velocity of light in a vacuum to its speed in that substance. Its value determines the extent to which light is refracted when entering or leaving the substance.
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica
Encyclopedia

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.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
Capturing both the absorption and phase coefficients of the index of refraction can help to reconstruct the image.
If the distillation separation of the methanol is good, you could try measuring the index of refraction.
Our experiments and simulations demonstrate the resonant behavior for the index of refraction.
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