# Question about index of refraction

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1. Jan 9, 2016

### Cozma Alex

according to wikiedia i can express the index as n= √(εrμr)
but i also know that the index of refraction depends of the wavelenght but i dont see any λ in the equation, so .... why?

Last edited by a moderator: Jan 9, 2016
2. Jan 9, 2016

### Orodruin

Staff Emeritus
The permeability and permittivity will generally depend on wavelength.