The refractive index of glass is 1.55 What is its polarising angle? Determine the angle of refraction for the polarising angle.

Explanation

If the refractive index of glass relative to air be `mu` and polarising angle be `i_(p)`, then according to Brewster's law we have,
` mu = tani_(p) " " or, tan i_(p) = 1.55`
`therefore " " i_(p) = tan^(-1)(1.55) = 57.17^(@)`
Again for incidence at the polarising angle,
`i_(p) + r = 90^(@)` [here r = angle of refraction ]
or, r = `90^(@) - i_(p) = 90^(@) - 57.17^(@) = 32.83^(@)`