# refractive index

refractive index
[1830-40]

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also called  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.

Some typical refractive indices for yellow light (wavelength equal to 589 nanometres [10-9 metre]) are the following: air, 1.0002; water, 1.333; crown glass, 1.517; dense flint glass, 1.655; and diamond, 2.417. The variation of refractive index with wavelength is the source of chromatic aberration in lenses. The refractive index of X-rays (X-ray) is slightly less than 1.0, which means that an X-ray entering a piece of glass from air will be bent away from the normal, unlike a ray of light, which will be bent toward the normal. The equation n = c/v in this case indicates, correctly, that the velocity of X-rays in glass and in other materials is greater than its velocity in empty space.

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Universalium. 2010.

### См. также в других словарях:

• Refractive index — Refractive Re*fract ive (r?*fr?kt ?v), a. [Cf. F. r[ e]fractif. See {Refract}.] Serving or having power to refract, or turn from a direct course; pertaining to refraction; as, refractive surfaces; refractive powers. [1913 Webster] {Refractive… …   The Collaborative International Dictionary of English

• Refractive index — Index In dex, n.; pl. E. {Indexes}, L. {Indices}(?). [L.: cf. F. index. See {Indicate}, {Diction}.] [1913 Webster] 1. That which points out; that which shows, indicates, manifests, or discloses; as, the increasing unemployment rate is an index of …   The Collaborative International Dictionary of English

• refractive index — n INDEX OF REFRACTION * * * the refractive power of a medium compared with that of air, which is assumed to be 1. Symbol n, n, or nD …   Medical dictionary

• refractive index — n. INDEX OF REFRACTION …   English World dictionary

• Refractive index — Refraction of light at the interface between two media. In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum… …   Wikipedia

• refractive index — lūžio rodiklis statusas T sritis automatika atitikmenys: angl. index of refraction; refraction index; refractive index vok. Brechungsindex, m; Brechungsverhältnis, n; Brechungszahl, f; Brechzahl, f; Refraktionsindex, m rus. индекс преломления, m; …   Automatikos terminų žodynas

• refractive index — lūžio rodiklis statusas T sritis chemija apibrėžtis Medžiagos konstanta, apibūdinanti jos savybę laužti šviesos bangas. atitikmenys: angl. index of refraction; refraction index; refractive index rus. индекс преломления; коэффициент рефракции;… …   Chemijos terminų aiškinamasis žodynas

• refractive index — noun the ratio of the velocity of light in a vacuum to that in a medium • Syn: ↑index of refraction • Hypernyms: ↑ratio * * * reˌfractive ˈindex 7 [refractive index] noun …   Useful english dictionary

• refractive index — lūžio rodiklis statusas T sritis Standartizacija ir metrologija apibrėžtis Esant nesugeriančiai terpei, tai elektromagnetinės spinduliuotės sklidimo greičio vakuume ir tam tikro dažnio elektromagnetinės spinduliuotės fazinio greičio terpėje… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

• refractive index — lūžio rodiklis statusas T sritis Standartizacija ir metrologija apibrėžtis Medžiagos parametras, apibūdinantis jos savybę laužti šviesos bangas. atitikmenys: angl. refraction index; refractive index vok. Brechungsindex, m rus. показатель… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

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