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. `1.647`
B. `1.523`
C. `1.489`
D. none of these

Answer

A

Explanation

`._(w)mu_(g) = (mu_(g))/(mu_(w)) = tan theta_(P)`
`mu_(g) = mu_(w) tan theta_(P) = (3)/(4) tan 51 = 1.647`