A beam of light passing through water strikes a glass plate immersed in water . The reflected beam is completely plane polarized if the angle of inccidence is `48^@`. The refractive index of water is `(4//3)`. Calculate the refractive index of glass.

Explanation

Since the reflected light is plane `48^@` is the polarising angle
`theta_p=48^@,n_w=4/3,n_g=?`
Refraction index of glass with respect of water,
`w^ng=n_g/n_w`
By Brewster's law
`w^ng=n_g/n_w=tantheta_p`
`thereforen_g=n_w tantheta_p=4/3 tan48^@=4/3 times1.1106=1.48`