Light testing 123
Classical Mechanics
Level
1
-
The path of a light ray from air to two different media A and B for a given angle of incidence as shown :
- QUESTION 1--> IF n A and n B are the refractive indices of two media then
- 1--> n A = n B
- 2--> n A > n B
- 3--> n A < n B
-
4 --> cannot be said
-
QUESTION 2--> IF angle of incidence is increased in both the media then angle of refraction will
- 1 --> increases
- 2 --> decreases
- 3 --> remain same
- 4--> becomes zero in medium A and will remain same in medium B
- NOTE ---> if your answer : cannot be said and decreases then write
- 42
The answer is 31.
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1 solution
Since the light ray goes undeviated in the first medium, the refractive indices of both air and the medium A are equal i.e both are 1 , but as we know that when light travels from rarer to denser medium, it bends towards the normal. Hence refractive index of medium B is greater than 1 .
This can also be seen by using Snell's law of refraction , which states that μ 1 sin i = μ 2 sin r where μ 1 and μ 2 are the refractive indices of first and the second medium respectively and i and r denote the angles of incidence and refraction respectively.
Again by using Snell's law, we see that since μ 1 and μ 2 are fixed for the media, but increasing the angle of incidence will also increase the angle of refraction in both cases.
Hence the answer becomes 3 1 .