Question

Assertion (A): In refraction through a glass slab, the emergent ray is parallel to the incident ray but in refraction through a glass prism, the emergent ray is not parallel to the incident ray.

Reason (R): The emergent ray of light in a glass prism is not parallel to the incident ray of light because the opposite faces of glass prism (where refraction takes place) are not parallel to one another. The opposite faces of a glass slab are, however, parallel to one another.

Options

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is correct explanation of the assertion.

Explanation:

The assertion is true because a rectangular glass slab has parallel refracting faces, causing equal and opposite bending of light that keeps the emergent ray parallel to the incident ray. Conversely, a prism has non-parallel, inclined refracting faces, which prevents the rays from realigning. This also serves as the correct explanation because the geometric parallelism (or lack thereof) of the opposing faces directly dictates whether the incident and emergent light paths remain parallel.