Question

(i)with a help of a ray diagram shoe that when lightfalls obiquely on a side of a rectangular glass slab the emergent ray is parallel to the incident ray .
(ii) list two factors on which laterl displacement depends.

Answer 1

1)  see diagram.

     BN & CN' are perpendicular to glass slab surfaces.
     BN'  ||  CN.    BC is the transversal line.
     So  angle of incidence at C = angle of refraction at B = r

     At  B:  Sin i / sin r = μ / 1
     At   C:    sin r / sin e  = 1/μ      (as incident medium = glass & refracted medium is air).
         Hence,   e = angle of emergence = i 
    Since the incident and emerging rays make the same angle i with the normal to the surfaces of the slab, they are parallel to each other.

2)   cos r = t /BC
   
   sin (i-r) = CE / BC
    CE = BC Sin(i-r) = t * sin(i-r) / cos r
       lateral displacement
  
     Factors :   t , μ  and i....       (r depends on μ & i).