A ray of light passes through a rectangular glass slab and through a triangular glass prism. Using proper ray diagram, explain in what way does the direction of the two emergent beams with respect to the incident beam of light differ.

In refraction of light through a glass slab, the emergent ray is parallel to the incident ray.

However, in refraction of light through a glass prism, the emergent ray is not parallel to the incident ray because the opposite faces of the glass prism are not parallel to one another and the emergent ray bends towards the base of the prism.