A ray of light travelling in glass enters glass water interface at an angle $\theta$. It finally emerges into air parallel to the surface of water. $ \mu_w=\large\frac{4}{3}$. What is the refractive index of glass.

Question

 

$(a)\;\frac{4}{3} \sin \theta \\ (b)\;\frac{1}{\sin \theta} \\ (c)\;\frac{4}{3} \\ (d)\;1 $