Q: When light of a creation wavelength is incident an a plane surface of a material at a glancing angle 30°, the reflected light is found to be completely plane polarized determine.
(a) refractive index of given material and
(b) angle of refraction.
Sol: (a) Angle of incident light with the surface is 30°. The angle of incidence = 90° – 30° = 60°. Since
reflected light is completely polarized, therefore incidence takes place at polarizing angle of incidence
ip.
∴ ip = 60°
Using Brewster’s law ,
? = tan ip
? = tan 60° = √3
(b) From Shell’s law
$\large \mu = \frac{sini}{sinr} $
$\large \sqrt{3} = \frac{sin60^o}{sinr} $
$\large sinr = \frac{sin60^o}{\sqrt{3}} = \frac{\sqrt{3}}{2 \times \sqrt{3}} $
or sin r = 1/2,
r = 30°