In this case, the extend of bending of the incident and emergent ray on the opposite and parallel sides of the glass slab is equal and opposite. The incident ray bends towards the nornal when travels from air to glass and bends away from the normal when travels through glass to air. Thus, the light emerges from a glass slab in a direction parallel with that in which it enters the glass slab. Also, though the emergent ray is parallel to the incident ray, the emergent ray shifts from its orginal path. Thst is, it gets letrally displaced.