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प्रश्न
Define the term absolute refractive index. The absolute refractive index of diamond is 2.42. What is the meaning of this statement? Refractive indices of media A, B C and D are given below:
|
Media |
Refractive index |
|
A |
1.33 |
|
B |
1.44 |
|
C |
1.52 |
|
D |
1.65 |
In which of these four media is the speed of light (i) minimum and (ii) maximum ?
Find the refractive index of medium C with respect to medium B.
उत्तर
Absolute refractive index: The refractive index of any medium with respect to the vacuum is called absolute refractive index of that medium.
The absolute refractive index of diamond is 2.42. This means the speed of light in diamond is 2.42 times slower than that in the vacuum.
`n=c/v=2.42`
Absolute refractive index: The refractive index of any medium with respect to the vacuum is called absolute refractive index of that medium.
The absolute refractive index of diamond is 2.42. This means the speed of light in diamond is 2.42 times slower than that in the vacuum.
`n_C/n_B=1.52/1.44=1.055-1.06`
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संबंधित प्रश्न
The speed of light in air is:
(a) 3 × 108 cm/s
(b) 3 × 108 mm/s
(c) 3 × 108 km/s
(d) 3 × 108 m/s
Which of the following diagrams shows the ray of light refracted correctly?
What is the unit of refractive index?
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.
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.
A light ray enters from medium A to medium B as shown in figure. The refractive index of medium B relative to A will be ______.
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?
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.
| The ability of medium to refract light is expressed in terms of its optical density. Optical density has a definite connotation. It is not the same as mass density. On comparing two media, the one with the large refractive index is optically denser medium than the other. The other medium with a lower refractive index is optically rarer. Also the speed of light through a given medium is inversely proportional to its optical density. |
- Determine the speed of light in diamond if the refractive index of diamond with respect to vacuum is 2.42. Speed of light in vacuum is 3 × 108 m/s.
- Refractive indices of glass, water and carbon disulphide are 1.5, 1.33 and 1.62 respectively. If a ray of light is incident in these media at the same angle (say θ), then write the increasing order of the angle of refraction in these media.
- (A) The speed of light in glass is 2 × 108 m/s and is water is 2.25 × 108 m/s.
(a) Which one of the two optically denser and why?
(b) A ray of light is incident normally at the water glass interface when it enters a thick glass container filled with water. What will happen to the path of the ray after entering the glass? Give reason.
OR
(B) The absolute refractive indices of glass and water are 4/3 and 3/2, respectively. If the speed of light in glass is 2 × 108 m/s, calculate the speed of light in (i) vacuum (ii) water.
