Refractive Index common Liquids, Solids and Gases
Refraction is an effect that occurs between transparent materials of different densities.
The Refractive Index - n - of a medium is a measure for how much the velocity of light is reduced inside the medium. The velocity of light in a medium can be expressed as
v = c / n (1)
where
v = velocity of light in the medium (m/s, ft/s)
c = speed of light in air or vacuum - approximately 3×108 m/s (or 299792458 m/s)
n = refractive index
The index of refraction is defined as
- "the speed of light in vacuum divided by the speed of light in the medium".
Eq. 1 modified
n = c / v (2)
Index of Refraction for Vacuum
- n = 1.00
Refractive Indices for some common Gases
| Gas | Refractive Index - n - |
|---|---|
| Acetone | 1.001090 |
| Air (-15 oC) | 1.00030942 |
| Air (0 oC) | 1.00029238 |
| Air (15 oC) | 1.00027712 |
| Air (30 oC) | 1.00026337 |
| Air (60 oC) | 1.00023958 |
| Alcohol, ethyl | 1.000878 |
| Alcohol, methyl | 1.000586 |
| Ammonia | 1.000376 |
| Argon | 1.000281 |
| Benzene | 1.001762 |
| Bromine | 1.001132 |
| Carbon dioxide | 1.000449 |
| Carbon disulphide | 1.001481 |
| Carbon monoxide | 1.000338 |
| Chlorine | 1.000773 |
| Chloroform | 1.001450 |
| Ether, ethyl | 1.001533 |
| Ether, methyl | 1.000891 |
| Helium | 1.000035 |
| Hydrochloric acid | 1.000447 |
| Hydrogen | 1.000132 |
| Methane | 1.000444 |
| Nitric oxide | 1.000297 |
| Nitrogen | 1.000298 |
| Nitrous oxide | 1.000516 |
| Oxygen | 1.000271 |
| Pentane | 1.000686 |
| Sulphur dioxide | 1.000686 |
| Water vapor | 1.000261 |
Index of Refraction for common Liquids
| Fluid | Refractive Index - n - |
|---|---|
| Acetic Acid | 1.37 |
| Acetone | 1.36 |
| Alcohol, ethyl (ethanol) | 1.36 |
| Alcohol, methyl (methanol) | 1.33 |
| Alcohol, propyl | 1.38 |
| Aniline | 1.586 |
| Benzene | 1.501 |
| Benzyl benzoate | 1.568 |
| Carbon disulfide | 1.63 |
| Carbon tetrachloride | 1.46 |
| Chlorobenzene | 1.525 |
| Chloroform | 1.44 |
| Decane | 1.41 |
| Dodecane | 1.41 |
| Ether | 1.35 |
| Ethylene glycol | 1.43 |
| Ethyl salicylate | 1.523 |
| Ethyl cinnamate | 1.559 |
| Trichlorofluoromethane refrigerant R-11 | 1.37 |
| Dichlorodifluoromethanerefrigerant R-12 | 1.29 |
| Chlorodifluoromethane refrigerant R-22 | 1.26 |
| Furan | 1.47 |
| Glyserine (Glycerol) | 1.47 |
| Heptane | 1.38 |
| Hexane | 1.37 |
| Hydrogen liquid | 1.0974 |
| Methyl salicylate | 1.538 |
| Methylene iodine | 1.737 |
| Milk | 1.35 |
| Octane | 1.40 |
| Oil, cedar | 1.516 |
| Oil, vegetable 50 oC | 1.47 |
| Oil, oiive | 1.46 |
| Oil, turpentine | 1.47 |
| Paraldehyde | 1.405 |
| Parafin, liquid | 1.48 |
| Propane | 1.34 |
| Propylene | 1.36 |
| Propylene glycol | 1.43 |
| Quinoline | 1.627 |
| Toluene | 1.497 |
| Turpentine (wood) | 1.47 |
| Water 0 oC | 1.33346 |
| Water 20 oC | 1.33283 |
| Water 100 oC | 1.31766 |
Example - Speed of Light in Air
The speed of light in air can be calculated as
v = (299792458 m/s) / 1.000293
= 299704645 m/s
Example - Speed of Light in Water
The approximate speed of light in water can be calculated as
v = (3×108 m/s) / 1.33
= 2.26 108 m/s
Index of Refraction for some common Solids
| Solid | Refractive Index - n - |
|---|---|
| Crown glass | 1.5 - 1.62 |
| Diamond | 2.417 |
| Flint glass | 1.57 - 1.75 |
| Ice | 1.31 |
| Plexiglas | 1.49 |
| Salt | 1.52 |
Example - Speed of Light in Glass
The approximate speed of light in glass can be calculated as
v = (3×108 m/s) / 1.6
= 1.88 108 m/s
Index of Refraction for some selected Polymers
| Polymer | Refractive Index - n - |
|---|---|
| Acrylic | 1.48 - 1.50 |
| Celulose Acetat | 1.46 - 1.50 |
| Epoxy | 1.6 |
| HDPE | 1.5 |
| Polycarbonate | 1.59 |
| PTFE | 1.35 |
| Polyester | 1.50 - 1.58 |
| Polystyrene | 1.6 |
| Vinylidene chloride | 1.6 - 1.63 |
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