In the above figure, when the prism is in its position of minimum deviation :
(i) The angle of incidence, $\left({\mathit{i}}_1\right)$ is equal to the angle of emergence $\left({\mathit{i}}_2\right)$,
(ii) The refracted may $\mathrm{PQ}$ is parallel to the base $\mathrm{BC}$ of the prism.