index of refraction

American  

noun

Optics.

1. 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. n

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index of refraction British  

noun

1. another name for refractive index

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index of refraction Scientific  

1. 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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Etymology

Origin of index of refraction

First recorded in 1820–30

Example Sentences

The difference in index of refraction between the two materials defines the angle of that bending.

From Scientific American • Nov. 18, 2022

Light entering a medium with a negative index of refraction, on the contrary, would bend backward, creating unexpected optical effects, such as a straw appearing to lean the wrong way.

From Scientific American • Nov. 18, 2022

Since the index of refraction varies with wavelength, the angles of refraction vary with wavelength.

From Textbooks • Aug. 12, 2015

A sequence of red to violet is produced, because the index of refraction increases steadily with decreasing wavelength.

From Textbooks • Aug. 12, 2015

Their minds had the same index of refraction, so that thoughts flashed back and forth between them effortlessly and without distortion.

From Mary Wollaston by Webster, Henry Kitchell