Question

The speed of light in air is 3.0x10^8ms/2. Calculate the refractive index of the material which the fibre is made.

Answer 1

Given,

Speed of light in air $v_1=3\times 10^8\ m/s$

Let speed of light in fibre is $v_2=1.8\times 10^8\ m/s$

So,

Refractive index of fibre $n_g=\dfrac{speed \ of light\ in\ vacuum}{speed\ of \ light\ in\ fibre}$

$n_g=\dfrac{3\times 10^8}{1.8\times 10^8}=1.67$

So, Refractive Index of fibre is 1.67