Question

If the refractive index for light going from air to diamond be 2.42, what will be the refractive index for light going from diamond to air?

Answer 1

Here,
$$\begin{gathered} {}^{air}n_{diamond}=2.42 \\ {}^{diamond}n_{air}=\frac{1}{{}^{air}{n}_{diamond}}=\frac{1}{2.42}=0.41 \end{gathered}$$