Draw the path of a ray of light when it enters one of the faces of a glass slab at an angle of nearly ${45}^{\circ }$. Label on it (i) angle of refraction, (ii) angle of emergence and (iii) lateral displacement.
OR
A student traces the path of a ray of light through a glass prism as shown in the diagram, but leaves it incomplete and unlabelled. Redraw and complete the diagram. Also label on it $\angle \mathit{i},\angle \mathit{e},\angle \mathit{r}$, and $\angle \mathrm{D}$.