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'.

Answer 1

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

3 × 10⁸  m s⁻¹⇒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.