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Question
The absolute refractive indices of two media 'A' and 'B' are 2.0 and 1.5 respectively. If the speed of light in medium 'B' is 2 × 108 m/s, calculate the speed of light in:
(i) vacuum,
(ii) medium 'A'.
Solution
Absolute refractive index of medium 'A', `mu_A=2.0`
Absolute refractive index of medium 'B', `mu_B=1.5`
(i) For medium 'B',
`1.5=c/((2xx10^8))`
`rArrc=2xx1.5xx10^8`
`rArrc=3xx10^8`
Speed of light in vacuum is ⇒v=cμA
⇒v=cμA.
(ii) For medium 'A',
`mu_A=c/v`
`rArrv=c/mu_A`
`rArrv=(3xx10^8)/2`
`rArrv=1.5xx10^8`
Thus, speed of light in medium 'A' is 1.5 x 108 m s-1.
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