A ray of light incident at an angle θ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5° and the prism is made of a material of refractive index 1.5, the angle of incidence is
Options:
(a) 7.5°.
(b) 5°.
(c) 15°.
(d) 2.5°