Question

${\lambda }_a$ and ${\lambda }_m$ are the wavelengths of a beam of light in air and medium respectively. If $\theta$ is the polarising angle, the correct relation between ${\lambda }_a,{\lambda }_m$ and $\theta$ is

• A. ${\lambda }_{\text{a }}={\lambda }_m{\tan }^2\theta$
• B. ${\lambda }_m={\lambda }_a{\tan }^2\theta$
• C. ${\lambda }_a={\lambda }_m\cot \theta$
• D. ${\lambda }_m={\lambda }_a\cot \theta$

Answer 1

Answer: (D)

We know, ${\lambda }_m=\frac{{\lambda }_a}{\mu }$
and $\mu =\tan \theta$
$\therefore {\lambda }_m=\frac{{\lambda }_a}{\tan \theta }={\lambda }_a\cot \theta$