Question

When an unpolarized light falls at a particular angle on a glass plate (placed in air), it is observed that the reflected beam is linearly polarized. The angle of refracted beam with respect to the normal is ___. ($\tan^{-1}(1.52) = 57.7^\circ$, refractive indices of air and glass are 1.00 and 1.52, respectively.)

• A. $39.6^\circ$
• B. $32.3^\circ$
• C. $42.6^\circ$
• D. $36.3^\circ$

Hint:

When reflected light is completely polarized, reflected and refracted rays are at $90^\circ$. Hence $r = 90^\circ - i_p$.

Answer 1

The Correct Option is B

The phenomenon described is polarization by reflection, which occurs at Brewster's angle $i_p$.
Brewster's Law states $\tan i_p = \mu$.
$i_p = \tan^{-1}(1.52) = 57.7^\circ$.
At this angle, the reflected and refracted rays are perpendicular to each other: $i_p + r = 90^\circ$.
The angle of refraction $r = 90^\circ - 57.7^\circ = 32.3^\circ$.