View source for Index of refraction

The '''index of refraction''' is a quantity that expresses the degree to which a medium [[refraction|refracts]] [[light]].  The index is given by <math>n=c/v_{phase}</math>, where ''c'' is the [[speed of light]] in a [[vacuum]] and <math>v_{phase}</math> is the [[phase velocity]] of light in the medium.  For media that [[absorption|absorb]] as well as refract light, the index of refraction is expressed as a [[complex number]] whose imaginary component expresses the absorption.

[[Category:Optics]]