Question

A light is incident on a glass slab. The angle of incidence is 54° while the angle of refraction is 30°. What will be the speed of light in the glass slab?

(a) v = 1.85 X 10^8m/s

(b) v = 2.85 X 10^8m/s

(c) v = 3.85 X 10^8m/s

(d) v = 4.85 X 10^8m/s

I got this question during an online exam.

I want to ask this question from Velocity of Light topic in portion Optics of Engineering Physics II

Answer 1

The correct answer is (a) v = 1.85 X 10^8m/s

For explanation: Using Snell’s law, refractive index of glass slab = sin i/sin r

Also, the refractive index of glass slab = c/v

Therefore, c/v = sin i/sin r

v = c X sin r/sin i

v = 3 X 10^8X sin 30^o/ sin 54^o

v = 1.85 X 10^8m/s.