Refractive index of glass is $\frac{3}{2}$. A ray of light travelling in glass is incident on glass-water surface at an angle 30° with normal. Will it be able to come out into the water. Refractive index of water = $\frac{4}{3}$.

Refractive index of glass = $n_1$ = $\frac{3}{2}$

Refractive index of glass = $n_2$ = $\frac{4}{3}$

Critical angle = c

Therefore, $Sinc$ = $\frac{n_2}{n_1}$ = 0.88

c = ${62}^0$

Since angle of incidence is less than critical angle, it'll be able to enter water