# Interaction between Brewster's angle and the critical angle

I have been studying the relation between Brewster's angle and the critical angle, and I am left with the following question:

\begin{align} \tanθ_p & =\frac{1}{\sinθ_c} \\ \tanθ_p & =\frac{n_1}{n_2} \\ \sinθ_c & =\frac{n_2}{n_1}, \end{align} where $$n_1$$ has to be greater than $$n_2$$.

For the critical angle, $$n_1$$ has to be greater $$n_2$$. Is there a similar rule for Brewster's angle as well: Does $$n_1$$ also have to be greater than $$n_2$$?

In other words, does the polarisation of light by reflection only happen when the wave is travelling in a less dense medium and hits a denser medium? Or can the polarisation of light by reflection happen when a wave is travelling in a denser medium and hits a less dense medium as well?

The Brewster angle $$\theta_B$$ is defined by $$\tan(\theta_B) = \frac{n_2}{n_1}.$$ Since the range of the tangent function over $$\theta_B\in(0,\pi/2)$$ covers all positive real numbers $$(0,\infty)$$, there will always be a Brewster's angle, where $$p$$-polarized light is not reflected, regardless of the combination of media. The only conclusion that you can draw from the fact that $$n_2>n_1$$ (resp. that $$n_1>n_2$$) is that you will have $$\theta_B> 45°$$ (resp. $$\theta_B < 45°$$).