Draw a labelled diagram to show refraction of light by a rectangular glass slab. Mark the incident ray, emergent ray, refracted ray, normal, angle of incidence, angle of refraction and lateral displacement.

A ray of light is incident at an angle of $45°$ at the interface of medium $\left(1\right)$ and medium $\left(2\right)$ as shown in the diagram. Redraw this diagram in your answer book and complete it. If the angle of refraction is $30°$, find the refractive index of medium $\left(2\right)$ w.r.t medium $\left(1\right)$. [Given : $\sin 45°=\frac{1}{\sqrt{2}}$ and $\sin 30°=\frac{1}{2}$]