Q. Unpolarised light is incident from air on a plane surface of a material of refractive index '$\mu$'. At a particular angle of incidence 'i', it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation ?
A) $i = \sin^{-1}\left(\frac{1}{\mu}\right)$
B) Reflected light is polarised with its electric vector perpendicular to the plane of incidence
C) Reflected light is polarised with its electric vector parallel to the plane of incidence
D) $i = \tan^{-1}\left(\frac{1}{\mu}\right)$
Explanation
[Solution] This is Brewster's angle ($i = \tan^{-1}\mu$); the reflected light is plane polarised with its electric vector perpendicular to the plane of incidence. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.