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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 of index of refraction
1820-30 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for index-of-refraction
Historical Examples
  • He'd gotten an index-of-refraction reading on crystals too small to be seen except through a microscope.

    The Hate Disease William Fitzgerald Jenkins
British Dictionary definitions for index-of-refraction

index of refraction

another name for refractive index
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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index-of-refraction in Science
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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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