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

By comparing the patterns in forward- and back-scattered light, they could estimate each particle's size and its refractive index, which describes how strongly light bends or scatters when it passes through a material.

From Science Daily • Nov. 17, 2025

To address this limitation, the team developed a material with a high refractive index and low loss for the infrared region.

From Science Daily • Mar. 28, 2024

This plate is almost transparent to the terahertz rays, but it has a higher refractive index than the surrounding air, so at each point of the plate, it changes the incident wave a little.

From Science Daily • Mar. 18, 2024

The index of refraction outside the fiber must be smaller than inside, a condition that is easily satisfied by coating the outside of the fiber with a material having an appropriate refractive index.

From Textbooks • Aug. 12, 2015

Its opacity is due to the presence of a very large number of solid particles, the blood corpuscles, having a higher refractive index than that of the liquid in which they float.

From Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 1 "Bisharin" to "Bohea" by Various