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Question
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`
Solution
4/6
Explanation:
Refractive index of material 2 with respect to material 1 is given by:
1n2 =`"speed of light in medium 1"/"speed of light in medium 2"`
By the same argument, refractive index of medium 1 with respect to medium 2 is given by:
2n1 = `"speed of light in medium 2"/"speed of lighht in medium 1"`=1/1n2
1n2 is `3/2` therefore, 2n1 will be 1/ `3/2`
Therefore, refractive index of light going from glass to air will be 4/6.
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(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.
