Question

A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is [MNR 1988; MP PMT 1999; Roorkee 2000; UPSEAT 2000; MP PET 2005]
A) 45? B) 39? C) 20? D) 30?

Answer 1

angle of prism is 60 as it is equilateral triangle
so angle of incidence =3/4*60=45=angle of emergence
by using formula
i+e=A +d
45+45=60+d
d=90-60
d=30