refractive index

American  

noun

Optics.

1. index of refraction.

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refractive index British  

noun

1.  ν.   μ.  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

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Etymology

Origin of refractive index

First recorded in 1830–40

Example Sentences

A key concept behind this discovery is the refractive index, which describes how much a material bends or slows light.

From Science Daily • Apr. 21, 2026

The key difference in this new approach is the use of molybdenum diselenide, which has a much higher refractive index.

From Science Daily • Apr. 5, 2026

Instead of trapping light inside solid matter, they confine it within subwavelength air cavities etched into a material with a very high refractive index.

From Science Daily • Mar. 24, 2026

"Excitons are very sensitive to the charge density in the material, and therefore we can change the refractive index of the material by applying a voltage," says Van de Groep.

From Science Daily • May 30, 2024

This relation depends upon the refractive index of the material, but as most color stones are of somewhat similar refractive indices, the above proportions are sufficiently accurate for all.

From A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public by Wade, Frank Bertram