Given:
[tex]\begin{gathered} n_i=1.00 \\ \theta_i=60\degree \\ \theta_r=18.5\degree \end{gathered}[/tex]
Required:
To find the value of nr.
Explanation:
The Snell's law is
[tex]\begin{gathered} n_i\sin\theta_i=n_r\sin\theta_r \\ \\ n_r=\frac{n_i\sin\theta i}{\sin\theta_r} \\ \\ =\frac{1.00\times\sin60}{\sin18.5} \\ \\ =\frac{1\times0.8660}{0.3173} \\ \\ =2.7292 \\ \\ n_r=2.73 \end{gathered}[/tex]
