A ray of light travelling in air enters a glass slab. Which of the following statements is/are correct? (i) Angle of incidence is greater than the angle of refraction. (ii) Angle of incidence is equal to angle of emergence. (iii) The emergent ray is parallel to the incident ray.

Correct option is B

Sol: The correct answer is (b) (i), (ii) and (iii)

When a ray of light travels from air (a less dense medium) into a glass slab (a more dense medium), the following principles of refraction apply:

(i) Angle of incidence is greater than the angle of refraction

• This statement is correct. According to Snell's Law, when light travels from a less dense medium (air) to a more dense medium (glass), it bends towards the normal. Hence, the angle of incidence is greater than the angle of refraction.

(ii) Angle of incidence is equal to the angle of emergence (ii):

• This statement is correct. When a ray of light emerges from the glass slab back into air, the angle of emergence is equal to the angle of incidence, provided the two surfaces of the glass slab are parallel.

(iii) The emergent ray is parallel to the incident ray (iii):

• This statement is correct. In a parallel-sided glass slab, the incident ray and the emergent ray are parallel to each other, but they are displaced laterally.

So, all the statements are correct.