Question

why emergent ray is parallel to incident ray in a rectangular slab

Answer 1

Since the refracting surfaces areparallel to each othe the emergent rays are parallel. ... Since the surfaces are parallel the ray inside the glass falls at the other surface at angle r and therefore the ray emerges at angle i that is the angle of incidence. Therefore the incident ray is parallel to the emergent ray.

Answer 2

The emergent Ray is parallel to incident ray because light comes back to the SAM e medium but I’d displaced