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प्रश्न
How refraction of light is related to refractive index?
उत्तर
For a given angle of incidence, the extent of refraction of light is different in different media.
- When the refractive index of the second medium is greater than the refractive index of the first medium, the refracted ray bends more towards the normal.
- When the refractive index of the first medium is greater than the refractive index of the second medium, the refracted ray bends away from the normal.
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संबंधित प्रश्न
If the refractive index of glass for light going from air to glass is 3/2, find the refractive index of air for light going from glass to air.
A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?
You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in Table.
| 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 | 2.42 |
The refractive index of diamond is 2.42. What is the meaning of this statement?
What name is given to the ratio of sine of angle of incidence to the sine of angle of refraction?
The refractive index of diamond is 2.42. What is the meaning of this statement in relation to the speed of light?
How is the refractive index of a material related to the speed of light in it?
Fill in the following blank with a suitable word:
When a ray of light goes from air into a clear material, you see the ray bend. How much the ray bends is determined by the ............... of the material.
Define Snell's law of refraction. A ray of light is incident on a glass slab at an angle of incidence of 60°. If the angle of refraction be 32.7°, calculate the refractive index of glass. (Given : sin 60° = 0.866, and sin 32.7° = 0.540).
The speed of light in air is 3 × 108 m/s. In medium X its speed is 2 × 108 m/s and in medium Y the speed of light is 2.5 × 108 m/s Calculate:
(a) air nx
(b) air nY
(c) x nY
Light enters from air into diamond which has a refractive index of 2.42. Calculate the speed of light in diamond. The speed of light in air is 3.0 × 108 ms−1.
The refractive index of glass for light going from air to glass is The refractive index for light going from glass to air will be:
(a) `1/3`
(b) `4/5`
(c) `4/6`
(d) `5/2`
The refractive index of glass for light going from air to glass is .
The refractive index for light going from glass to air will be:
(a) `1/3`
(b) `4/5`
(c) `4/6`
(d) `5/2`
The speed of light in substance X is 1.25 × 108 m/s and that in air is 3 × 108 m/s. The refractive index of this substance will be:
(a) 2.4
(b) 0.4
(c) 4.2
(d) 3.75
The refractive index of water is:
(a) 1.33
(b) 1.50
(c) 2.42
(d) 1.36
Refractive indices of water, sulphuric acid, glass and carbon disulphide are 1.33, 1.43, 1.53 and 1.63 respectively. the light travels slowest in:
(a) sulphuric acid
(b) glass
(c) water
(d) carbon disulphide
The refractive index of glass with respect to air is `3/2` and the refractive index of water with respect to air is `4/3`. The refractive index of glass with respect to water will be:
(a) 1.525
(b) 1.225
(c) 1.425
(d) 1.125
The following table gives the refractive indices of a few media:
| 1 | 2 | 3 | 4 | 5 | |
| Medium | Water | Crown glass | Rock salt | Ruby | Diamond |
| Refractive index | 1.33 | 1.52 | 1.54 | 1.71 | 2.42 |
Use this table to give an example of:
(i) a medium pair so that light speeds up when it goes from one of these medium to another.
(ii) a medium pair so that light slows down when it goes from one of these medium to another.
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.
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.
With the help of a ray diagram, state what is meant by refraction of light. State Snell’s law for refraction of light and also express it mathematically.
The refractive index of air with respect to glass is 2/3 and the refractive index of water with respect to air is 4/3. If the speed of light in glass is 2 × 108 m/s, find the speed of light in (a) air, (b) water.
Prove the statement.
If the angle of incidence and angle of emergence of a light ray falling on a glass slab are i and e respectively, prove that, i = e.
Refractive index of air : 1.0003 : : refractive index of water : _______
If the absolute refractive index of water is 1.36, find the speed of light in water. (Speed of light in vacuum = 3 × 108 m/s.)
Solve the following example.
Speed in first medium, v1 = 3 × 108 m/s
Speed in second medium, v2 = 2 × 108 m/s
Then 2n1 = ?
The velocity of light in a vacuum is 3 x 108 ms-1 and in glass is 2 x 108 ms-1. The refractive index of glass is ______.
Match the Columns:
| Column ‘A’ | Column ‘B’ |
| Refractive index of water | (a) 1.31 |
| (b) 1.36 | |
| (c) 1.33 |
What happens when a light ray passes from a rarer medium to a denser medium?
Match the pair:
| Group 'A' | Group 'B' | |
| Substance | Refractive index | |
| Air | (a) | 1.33 |
| (b) | 1.46 | |
| (c) | 1.0003 |
A light ray enters from medium A to medium B as shown in the figure.
Which one of the two media is denser w.r.t. other medium? Justify your answer.
A light ray enters from medium A to medium B as shown in the figure.
If the speed of light in medium A is `v_a` and in medium B is `v_b`, what is the refractive index of B with respect to A.
Absolute refractive indices of diamond and water are 2.42 and 1.33 respectively. Find the value of refractive index of water w.r.t. diamond.
- 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.
