When a ray of light passes through a rectangular glass slab, it undergoes refraction at both the surfaces of the slab.
The emergent ray is parallel to the incident ray but is displaced sideways.
Since the two refracting surfaces of a glass slab are parallel to each other, the angle of emergence is equal to the angle of incidence.
Hence, the emergent ray is parallel to the incident ray.
The perpendicular distance between the incident ray and the emergent ray is called lateral displacement.
If the ray of light is incident normally on the glass slab, there is no lateral displacement.
Q1. In refraction through a glass slab, the emergent ray is: A) Perpendicular to incident ray B) Inclined to incident ray C) Parallel to incident ray D) Opposite to incident ray Answer: C Q2. The distance between incident ray and emergent ray is called: A) Deviation B) Displacement C) Lateral displacement D) Refraction Answer: C Q3. Lateral displacement depends on: A) Thickness of slab only B) Angle of incidence only C) Refractive index only D) Thickness, angle of incidence and refractive index Answer: D Q4. If the thickness of the glass slab increases, lateral displacement: A) Decreases B) Remains same C) Becomes zero D) Increases Answer: D Q5. When light is incident normally on a glass slab, lateral displacement is: A) Maximum B) Minimum C) Zero D) Infinite Answer: C Q6. Angle of emergence in glass slab is: A) Greater than angle of incidence B) Less than angle of incidence C) Equal to angle of incidence D) Zero Answer: C Q7. Increase in refractive index of slab causes lateral displacement to: A) Decrease B) Remain constant C) Increase D) Become zero Answer: C Q8. Refraction through glass slab involves refraction at: A) One surface only B) Two parallel surfaces C) Three surfaces D) Curved surface Answer: B
A rectangular transparent medium with parallel surfaces.
Parallel to the incident ray.
Perpendicular distance between incident and emergent rays.
Normal incidence → no lateral displacement.
MCQs are frequently asked on lateral displacement, parallel emergent ray and factors affecting displacement.
