Question

In the glass slab experiment, a student measures the angle of incidence (∠i) in air and finds it to be 40°. He also measured the corresponding angle of refraction as well as the angle of emergence for this ray of light but lost their record. The most likely record of readings for the angle of refraction and angle of emergence will be:

(1) ∠r = 40° and ∠e = 50°
(2) ∠r > 40° and ∠e = 40°
(3) ∠r = 50° and ∠e = 40°
(4) ∠r < 40° and ∠e = 40°

Answer 1

When a light ray enters a glass slab then it bends towards the normal, so the angle of refraction becomes smaller than the angle of incidence. But, when it emerges from the slab into the air again, it bends away from the normal and becomes parallel to the incident ray, such that the angle of the emergence becomes equal to the angle of incidence.

Hence. the correct answer is option 4.