Refractive index

Refractive index: Refractive index is called the ratio of the speed of light in vacuum (c) and the speed of light in the medium (v), symbolized by the letter n being a dimensionless value.


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  • 1 relative refractive index
  • 2 Absolute refractive index
  • 3 Refractive indices for various materials
  • 4 Applications
  • 5 Sources

relative refractive index

It allows to compare the speeds 1 and 2 of two different media between media 1 with respect to 2 as a quotient between both:

Absolute refractive index

Since the speed of light in a vacuum is always greater than the speed of light in the medium, the index is always greater than or equal to unity. As it is deduced from the definition itself, the higher the absolute refractive index of a substance, the more slowly light will travel inside it.

Refractive indices for various materials

Light refraction at the interface between two media with different refractive indices (n 2 > n 1 ). Since the phase velocity is less in the second medium (v 2 <v 1 ), the angle of refraction? 2 is less than the angle of incidence? 1 (? 2 <? 1 ); that is, the ray in the middle of the major index is close to the normal vector.

Material Refractive index
Empty 1.00
Air 1,000294
Ice 1.31
Water 1.33
Ethyl alcohol 1.36
Ether 1.36
Methacrylate 1.49
Benzene 1.50
Glass 1.50
Gem salt 1.54
Sulfuric acid 1.63
Diamond 2.42
Quartz 1.54
Glycerin 1.47
Oleic acid 1.46
Methanol 1,3286
Paraffin 1.43
Jade 1.66
Amethyst 1.54 – 1.55
Amber 1.54
Jet 1.66
Emerald 1.56 – 1.58
Fluorite 1,433
Zircon 1.98


  • It is used for making lenses.
  • In chemistry to determine the purity of chemical reagents.
  • In computer science for the rendering of reflective materials in 3D graphics.


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