Question

A parallel beam of monochromatic unpolarised light is incident on a transparent dielectric plate of refractive index $\frac{1}{\sqrt{3}}$. The reflected beam is completely polarised. Then the angle of incidence is

• A. 30${}^o$
• B. 60${}^o$
• C. 45${}^o$
• D. 75${}^o$

Answer 1

The correct option is A 30${}^o$

Using Brewster law, $\tan i_p=\mu$

$\Rightarrow i_p={\tan }^{-1}\mu$

$={\tan }^{-1}\left(\frac{1}{\sqrt{3}}\right)$

$={30}^o$