Q1. [1] § 9.2.3 Sign Convention for Reflection by Spherical Mirrors § 9.3.1 Refraction through a Rectangular Glass Slab § 9.3.5 Image Formation in Lenses Using Ray Diagrams
An optical device 'X' is placed obliquely in the path of a narrow parallel beam of light. If the emergent beam gets displaced laterally, the device 'X' is :
- (a) plane mirror
- (b) convex lens
- (c) glass slab
- (d) glass prism
Previously asked in CBSE board exam
2025 31/4/1 Q11
Generated by claude-sonnet-4-6 · 2026-06-15 06:50 · grounding rag
Model Answer
(c) glass slab
When light passes obliquely through a glass slab, the emergent ray is parallel to the incident ray but shifted sideways — this sideward shift is called lateral displacement.
Source: Light – Reflection and Refraction, Section 9.3.1
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Explanation
The key phrase is "laterally displaced" — this is the defining property of refraction through a rectangular glass slab. The two parallel faces cause equal and opposite bending, so the ray emerges parallel but shifted. A prism disperses light; a lens converges/diverges it; a plane mirror reflects it. Only a glass slab produces lateral displacement without change in direction.
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