When light of a certain wavelength is incident on a plane surface of a material at a glancing angle `30^(@)`, the reflected light is found to be compleley plane polarized determine.
a) refractive index of given material and
b) angle of refraction.

Explanation

a) Angle of incident light with the surface is `30^(@)`. The angle of incidence `= 90^(@)-30^(@)=60^(@)`. Since reflected light is compeletely polarized, therefore incidence takes place at polarizing angle of incidence `theta_(p)`.
`:. theta_(p)=60^(@)`
Using Brewster's law
`mu = tan theta_(p) = tan 60^(@) mu = sqrt(3)`
b) Form Snell's law
`mu= (sin i)/(sin r) :. sqrt(3) = (sin 60^(@))/(sin r)`
or `sin r = (sqrt(3))/(2)xx(1)/(sqrt(3))= (1)/(2), r = 30^(@)` .