Question

Time taken by light to cross a glass slab of the
thickness 4 mm and refractive index 3 is?​

Answer 1

Answer:

The answer will be 4 * 10^-11 second.

Explanation:

Given;

        Thickness of glass slab = 4mm;

        Refractive index = 3;

Refractive index of glass = velocity of light in vacuum / velocity of light in the medium

Thus, μ = (3 * 10^8) / velocity of light in that medium

         3 = (3 * 10^8) / velocity of light in that medium

velocity of light in that medium = (3 * 10^8) / 3

                                                     = 10^8 m/s

Time to be taken = Distance to be travelled / speed of light;

Thus, time = (4 * 10^-3) / 10^8

                  = 4 / (10^8 * 10 ^3)

                  = 4 / 10^11 sec = 4 * 10^-11 second.

That's all.