Question

A ray of light falls on a transparent glass slab of refractive index $ 1.62 $ . If the reflected ray and the refracted ray are mutually perpendicular, the angle of incidence is

• A. $ tan^{-1}\, (1.62) $
• B. $ tan^{-1}\, \left(\frac{1}{1.62}\right) $
• C. $ tan^{-1}\, (1.33) $
• D. $ tan^{-1}\, \left(\frac{1}{1.33}\right) $

Answer 1

Answer: (A)

Brewster discovered that when a beam of unpolarised light is reflected from a transparent medium (refractive index $=\mu)$, the reflected light is completely plane polarised at a certain angle of incidence (called the angle of polarisation $\theta_{p}$ )
Also, $\mu=\tan\, \theta_{p}$
$\therefore $ Here, $\theta_{p}=\theta_{i}=\tan ^{-1}(1.62)$