Question

What is the difference between the Brewster angle and the critical angle?

Answer 1

Brewster angle and critical angle are incident angles that are related to completely different phenomena of polarization and total internal reflection. There is not much similarity except that both are incident angles

Brewster angle
It is the incident angle for an unpolarized light to become completely polarized after reflecting from a surface.
Brewster's angle can be written as,
_B = tan^-1(n2/n1)
Where n1 is the refractive index of the initial medium where the light propagates and n2 is the refractive index of the other medium.

Critical angle
It is the incident angle at which the refracted angle become 90 degree or stays parallel with the interface of the two medium.
The critical angle can be written as,
_C = sin^-1(n2/n1)
Where n1 is the refractive index of the medium from which the light incidents and n2 is the refractive index of the other medium.