Quick Answer: The Glass Slab is a transparent rectangular glass block for ray optics practicals, used to show refraction, lateral displacement, the angles of incidence and refraction, and Snell’s law.
Last updated: October 2026
Key Features
Rectangular block with parallel faces for studying lateral displacement.
Shows how a light ray changes direction from air into glass and back into air.
Used for measuring the angle of incidence and angle of refraction.
Works with ray boxes, low-power laser sources, pins, protractors and white paper.
About This Product
The slab is laid on white paper and its outline traced. An incident ray is drawn toward one face, and pins, a ray box or a low-power laser mark the path of light through the glass and the emergent ray from the opposite face. With the slab removed, the marked points are joined and the angles measured with a protractor, giving a complete ray diagram for refraction at parallel surfaces.
Frequently Asked Questions
Q1. What happens to the emergent ray? It leaves the opposite face laterally displaced from the incident ray but still parallel to it, which students measure as lateral displacement.
Q2. Can a laser be used instead of pins? Yes. A ray box or a low-power laser source can mark the light path, but the beam should never be pointed directly into the eyes.
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