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प्रश्न
What is meant by the refractive index of a substance?
उत्तर
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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संबंधित प्रश्न
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 |
Refractive indices of carbon disulphide and ethyl alcohol are 1.63 and 1.36 respectively. Which is optically denser?
The refractive index of diamond is 2.42. What is the meaning of this statement in relation to the speed of light?
The refractive indices of four materials A, B, C and D are 1.33, 1.43, 1.71 and 1.52 respectively. When the light rays pass from air into these materials, they refract the maximum in:
(a) material A
(b) material B
(c) material C
(d) material D
State Snell’s law of refraction of light. Write an expression to relate refractive index of a medium with speed of light in vacuum.
The refractive index of a medium ‘a’ with respect to medium ‘b’ is 2/3 and the refractive index of medium ‘b’ with respect to medium ‘c’ is 4/3. Find the refractive index of medium ‘c’ with respect to medium ‘a’.
State the law of refraction of light that defines the refractive index of a medium with respect to the other. Express it mathematically. How is refractive index of any medium 'A' with respect to a medium 'B' related to the speed of propagation of light in two media A and B? State the name of this constant when one medium is vacuum or air.
The refractive indices of glass and water with respect to vacuum are 3/2 and 4/3 respectively. If the speed of light in glass is 2 × 108m/s, find the speed of light in (i) vacuum, (ii) water.
Fill in the blank and Explain the completed sentences.
Refractive index depends on the ______ of light.
Solve the example.
If the absolute refractive indices of glass and water are 3/2 and 4/3 respectively, what is the refractive index of glass with respect to water?
Noor, a young student, was trying to demonstrate some properties of light in her Science project work. She kept ‘X’ inside the box (as shown in the figure) and with the help of a laser pointer made light rays pass through the holes on one side of the box. She had a small butter-paper screen to see the spots of light being cast as they emerged.
If the object inside the box was made of a material with a refractive index less than 1.5 then the ______.
- Explain why the refractive index of any material with respect to air is always greater 1.
- In the figure below a light ray travels from air into the semi-circular plastic block. Give a reason why the ray does not deviate at the semi-circular boundary of the plastic block.
- Complete the ray diagram of the above scenario when the light ray comes out of the plastic block from the top flat end.
