What it shows:
When unpolarized light is reflected from a non-metallic surface, the reflected ray is plane polarized parallel to the reflecting surface if
θi + θr = 90°
or
tanθi = n
where θi = incident ray (Brewster's angle), θr = refracted ray, n = refractive index
How it works:
We use a black vinyl sheet 1m×4m as the reflecting surface, which has a Brewster angle of 57°. A theatrical spot lamp 1 is used to give a 50cm circle...
Read more about Brewster's Angle