Physics - Wave Optics Question with Solution | TestHub

According to Brewster's law, the refractive index of glass with respect to air is given by $\mu =\tan \theta$, where $\theta$ is the polarising angle.

The refractive index is also equal to the ratio of the wavelength of light in air to the wavelength of light in the medium:

$\mu =\frac{{\lambda }_a}{{\lambda }_g}$

Equating the two expressions for $\mu$, we get:

$\frac{{\lambda }_a}{{\lambda }_g}=\tan \theta$

${\lambda }_g=\frac{{\lambda }_a}{\tan \theta }$

${\lambda }_g={\lambda }_a\cot \theta$

Answer: ${\lambda }_g={\lambda }_a\cot \theta$