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Question
What is meant by the refractive index of a substance?
Solution
If i is the angle of incidence and r is the angle of refraction, we get:
`sin i/sin r` = constant
This constant value is called the refractive index of the medium in which light enters through air. Refractive index of a medium can also be expressed in terms of speed of light as follows:
1n2 =`"speed of light in medium 1"/"speed of light in medium 2"`
Here, 1n2 is the refractive index of medium 2 with respect to medium 1.
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RELATED QUESTIONS
Find out, from Table, the medium having highest optical density. Also find the medium with lowest optical density.
| Material medium | Refractive index | Material medium | Refractive index |
| Air | 1.0003 | Canada Balsam | 1.53 |
| Ice | 1.31 | – | – |
| Water | 1.33 | Rock salt | 1.54 |
| Alcohol | 1.36 | – | – |
| Kerosene | 1.44 | Carbon disulphide | 1.63 |
| Fused quartz | 1.46 | Dense flint glass | 1.65 |
| Turpentine oil | 1.47 | Ruby | 1.71 |
| Benzene | 1.50 | Sapphire | 1.77 |
| Crown glass | 1.52 | Diamond | .42 |
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(a) 1.33
(b) 1.50
(c) 2.42
(d) 1.36
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