Explain Brewster’s law.

When unpolarized light is incident on a transparent reflecting surface at polarizing angle, then the reflected light is completely plane polarized and the reflected and refracted light are perpendicular to each other.
$\mathrm{\mu }=\tan {\mathrm{\theta }}_{\mathrm{p}},\text{ where }{\mathrm{\theta }}_{\mathrm{p}}$ is angle of polarization or Brewster's angle.