See soorce fer Refractive index

In [[optics]] the '''refractive index''' or '''index o refraction''' ''n'' o a substance ([[optical medium]]) is a [[dimensionless]] nummer that describes hou [[EM radiation|licht]], or ony ither [[radiation]], propagates throu that medium. It is defined as 
:<math>n=\frac{c}{v}</math>,
whaur ''c'' is the [[speed o licht]] in [[vacuum]] an ''v'' is the speed o licht in the substance. For ensaumple, the refractive index o [[watter]] is 1.33, meanin that licht traivels 1.33 times slawer in watter nor it daes in vacuum.

{{DEFAULTSORT:Refractive Index}}
[[Category:Optics]]
[[Category:Concepts in pheesics]]
[[Category:Optical mineralogy]]
[[Category:Gless pheesics]]
[[Category:Dimensionless nummers]]
[[Category:Pheesical quantities]]