In your laboratory you trace the path of light rays through a glass slab for different values of angle of incidence ($\angle i$) and in each case measure the values of the corresponding angle of refraction ($\angle r$) and angle of emergence ($\angle e$). On the basis of your observations your correct conclusion is:

When a ray of light enters a rectangular glass slab from air (an optically rarer medium) to glass (an optically denser medium), it bends towards the normal. Therefore, the angle of incidence ($\angle i$) is greater than the angle of refraction ($\angle r$), i.e., $\angle i > \angle r$.

When the light ray emerges from the opposite parallel face of the glass slab back into the air, it bends away from the normal. Since the two refracting surfaces of the slab are parallel, the lateral bending at the second surface exactly compensates for the bending at the first surface. Thus, the emergent ray is parallel to the incident ray, which means the angle of emergence ($\angle e$) is nearly equal to the angle of incidence ($\angle i$).

• Option a is correct because it accurately states $\angle i > \angle r$ and $\angle i \approx \angle e$.
• Option b is incorrect because $\angle i$ is greater than $\angle r$, not less.
• Option c is incorrect because $\angle i$ is nearly equal to $\angle e$, not greater than it.
• Option d is incorrect because $\angle i$ is nearly equal to $\angle e$ and greater than $\angle r$.