(a) (i) Define refractive index of a medium in terms of speed of light. (ii) Derive the relation for the refractive index (\mu) of a prism in terms of angle of minimum deviation (\delta_{\text{m}}) and angle of prism (A). (iii) A ray of light QP is incident normally on the face BC of a triangular prism ABC of refractive index $1\cdot5$ kept in air, as shown in the figure. Trace the path of the ray as it passes through the prism and give relevant explanation.