Question

A ray of light in air is incident on a glass plate at polarising angle of incidence. It suffers a deviation of ${22}^{\circ }$ on entering glass. The angle of polarization is :

• A. ${90}^{\circ }$
• B. ${56}^{\circ }$
• C. ${68}^{\circ }$
• D. $Zero$

Answer 1

The correct option is B ${56}^{\circ }$

Let $\mu$ be the refractive index of glass
From snell's law
$\frac{sini}{sin\gamma }=\mu ;Here\gamma =i-{22}^0$
$\frac{sini}{sin(i-22)}=\mu$
As it is at polarization angle of incidence
$\mu =tani$
$\frac{sini}{sin(i-22)}=\frac{sini}{cosi}$
$cosi=sin(i-22)$
$sin(90-i)=sin(i-22)$
$90-i=i-22$
$112=2i;i={56}^0$