A ray of light travels in the fashion as shown in the figure. After passing through water the ray grazes along the water air interface. The value of µg in terms of i is

$\frac{1}{\sin i}$ $\frac{3}{4 \sin i}$ $\frac{4}{3 \sin i}$ none of these

$\frac{1}{\sin i}$

We have $\frac{4}{3} \sin C=1$ Again  $\mu_g \sin i=\frac{4}{3} \sin C=1 $ ∴  $\mu_g=\frac{1}{\sin i}$ ∴ (a)