Typical Values
| Material | n |
|---|---|
| Gases at 0 °C and 1 atm | |
| Air | 1.000293 |
| Helium | 1.000036 |
| Hydrogen | 1.000132 |
| Carbon dioxide | 1.00045 |
| Liquids at 20 °C | |
| Water | 1.333 |
| Ethanol | 1.36 |
| Benzene | 1.501 |
| Solids | |
| Ice | 1.309 |
| Fused silica | 1.46 |
| PMMA | 1.49 |
| Crown glass (typical) | 1.52 |
| Flint glass (typical) | 1.62 |
| Diamond | 2.42 |
For visible light most transparent media have refractive indices between 1 and 2. A few examples are given in the table to the right. These values are measured at the yellow doublet sodium D-line, with a wavelength of 589 nanometers, as is conventionally done. Gases at atmospheric pressure have refractive indices close to 1 because of their low density. Most plastics have refractive indices in the range from 1.3 to 1.7, but some high-refractive-index polymers can have a value as high as 1.76.
For infrared light refractive indices can be considerably higher. Germanium is transparent in this region and has a refractive index of about 4, making it an important material for infrared optics.
Read more about this topic: Refractive Index
Famous quotes containing the words typical and/or values:
“The books may say that nine-month-olds crawl, say their first words, and are afraid of strangers. Your exuberantly concrete and special nine-month-old hasn’t read them. She may be walking already, not saying a word and smiling gleefully at every stranger she sees. . . . You can support her best by helping her learn what she’s trying to learn, not what the books say a typical child ought to be learning.”
—Amy Laura Dombro (20th century)
“Normality highly values its normal man. It educates children to lose themselves and to become absurd, and thus to be normal. Normal men have killed perhaps 100,000,000 of their fellow normal men in the last fifty years.”
—R.D. (Ronald David)