Q.
For refraction through a plane glass slab, dimension $d$ is called
Ray Optics and Optical Instruments
Solution:
For a rectangular slab, refraction takes place at two interfaces (air-glass and glass-air).
It is easily seen from diagram that $r_{2}=i_{1}$,
i.e., the emergent ray is parallel to the incident ray $-$ there is no deviation,
but it undergoes a lateral shift.
