While tracing the path of a ray of light through a rectangular glass slab, the four students I, II, III and IV arrived at the following different conclusions : Student I : Angle of incidence > Angle of emergence. Student II : Angle of refraction > Angle of emergence. Student III : Emergent ray is parallel to refracted ray. Student IV : Emergent ray is parallel to incident ray. The correct conclusion has been drawn by the student

When a ray of light enters a rectangular glass slab:

1. At the first interface (air to glass), it bends towards the normal ($\angle r < \angle i$).
2. At the second interface (glass to air), it bends away from the normal by the same magnitude because the surfaces are parallel.
3. Consequently, the angle of incidence ($\angle i$) equals the angle of emergence ($\angle e$).
4. This makes the emergent ray parallel to the incident ray, although it is shifted sideways (lateral displacement).

• Student I is wrong because $\angle i = \angle e$.
• Student II is wrong because $\angle e$ is usually greater than $\angle r$.
• Student III is wrong because the emergent ray is parallel to the incident ray, not the refracted ray (which is inside the slab).