Critical angle
\(\text { Sini i }_{c}=\frac{\mu_{ R }}{\mu_{ D }}=\frac{ u _{ D }}{ u _{ R }}=\frac{1.5}{2}=\frac{3}{4}\)
\(i _{c}=\sin ^{-1}\left(\frac{3}{4}\right)\)
\(\sin i_{c}=\frac{\mu_{R}}{\mu_{D}}=\frac{u_{D}}{u_{R}}\)
\(i_{c}=\sin ^{-1}\left(\frac{3}{4}\right)\)
$\left(\right.$ આપેલ $\left.\mu_{r}=1\right)$