A beam of light travelling in water strikes a glass plate, which is also immersed in water. When the angle of incidence is ` 51^@`, the reflected beam is found to be plane polarised . What is the refractive index of glass if the refractive index of water is `(4)/3`? `[tan 51^(@)=1.235]`

Options

A. `1.646`
B. `1.325`
C. `2.123`
D. `1.987`

Answer

A

Explanation

According to Brewster's law,
`""_(w)n_g=tan i_p= tan51^(@)=1.235` ltbvrgt `:. ""_(w) n_g=(""_(a)n_g)/(""_(a) n_w) " " :. ""_(a)n_g=""_(w) n_g xx ""_(a) n_w=1.234 xx (4)/3=1.646`