
$\begin{aligned}
& i=\theta_c \
& \Rightarrow i=\sin ^{-1}\left(\frac{1}{\mu}\right) \
& \Rightarrow i=45^{\circ}
\end{aligned}andaccordingtosnell′slaw\begin{aligned}
& 1 \sin 45^{\circ}=\sqrt{2} \sin \mathrm{r} \
& \Rightarrow \mathrm{r}=30^{\circ}
\end{aligned}$
Lateral displacement Δ=cosrtsin(i−r) $\begin{aligned}
& \Rightarrow \Delta=\frac{4 \sqrt{3} \times \sin 15^{\circ}}{\cos 30^{\circ}} \
& \Rightarrow \Delta=2 \mathrm{~cm}
\end{aligned}$