Question

A ray of light is incident at an angle of incidence of 60° on the glass slab of refractive index `sqrt3`. After refraction the light ray emerges out from other parallel faces and the lateral shift between the incident ray and emergent ray is `4/sqrt3` cm. The thickness of the glass slab is ..........

Answer 1

Here, L = Lateral shift

L = `(d sin (i - r))/cos r`

By Snell’s law,

1 × sin i = `sqrt3` sin r

sin 60° = `sqrt3` sin r

sin r = `1/2`

r = 30°

So, `4sqrt3 = (d sin (60° - 30°))/(cos 30°)`

`4sqrt3` = d tan 30°

`4sqrt3 = d 1/sqrt3`

d = 12 cm