Science (086) — AI-generated practice question

The emergent ray is parallel to the incident ray but slightly shifted sideways (laterally displaced).

At surface AB (air → glass): Light travels from a rarer to a denser medium, so it bends towards the normal.

At surface CD (glass → air): Light travels from a denser to a rarer medium, so it bends away from the normal by an equal amount.

Since both parallel surfaces cause equal and opposite bending, the two effects cancel out, and the emergent ray emerges parallel to the incident ray, though laterally displaced.

Source: Chapter 9, Section 9.3.1 — Refraction through a Rectangular Glass Slab

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• The key conclusion (parallel + lateral shift) is worth 1 mark; explaining refraction at each of the two surfaces is worth the remaining 2 marks.
• Always name the two surfaces/interfaces and state the direction of bending (towards/away from normal) with the reason (rarer→denser / denser→rarer).
• The phrase "equal and opposite bending" is the textbook explanation — use it directly.
• Do not forget to mention lateral displacement; many students miss it.