Question

After tracing the path of rays of light through a glass slab for three different angles of incidence, a student measured the corresponding values angle of refraction r and angle of emergence e and recorded them in the table given below: (1)
S. No.
∠i
∠i
∠e
I
30°
20°
31°
II
40°
25°
40°
III
50°
31°
49°
The correct observations are:
(A) I and II
(B) II and III
(C) I and III
(D) I, II and III

Answer 1

Explanation:

The correct observations are:

(A) I and II

(B) II and III

(C) I and III✔️✔️

(D) I, II and III

Answer 2

(D) I, II and III

Explanation:

When light is refracted through a glass slab, angle of incidence = angle of emergence. So ∠i = ∠e. The light passes from rarer medium (air) to the denser medium (glass). So the light ray will bend towards the normal. Hence angle of refraction will be less than the angle of incidence or angle of emergence.

So Option D is correct. I, II and III are all correct.

Though there is slight difference in I and III between angles of incidence and emergence, it is negligible.