index of refraction

In optics, a property of mediums through which light passes, the ratio of the velocity of light in a vacuum (c) to its velocity in the medium. It varies with the wavelength of the light. The symbol is n.

The index of refraction can also be expressed in terms of the permeability and dielectric constant of the medium:

$An equation. n equals the fraction c over v, or equals the square root of the fraction whose numerator is mu times epsilon and whose denominator is mu sub oh time epsilon sub oh$ ,

where μ₀ and ε₀ represent the permeability and dielectric constant, respectively, of the vacuum.

Some Examples of Refraction Indices
Material	Index of refraction at 546.1 nm
phosphate crown glass	1.52736
borosilicate crown glass	1.51872
crown glass	1.51314
dense crown glass	1.60994
crown flint glass	1.51978
flint glass	1.60718
water at 30°C (589 nm)	1.33230
air at 15°C, 1 atm pressure	1.27782
fused silica	1.46008

Schott Optical Glass.
Schott Glass Technologies, Inc.