Question

A ray of unpolarised light is incident an a glass plate of refractive index 1,54 at polarising angle of refraction is

Answer 1

So for angles of incidence greater than 48.6-degrees, TIR occurs. But 48.6 degrees is the critical angle only for the water-air boundary. The actual value of the critical angle is dependent upon the two materials on either side of the boundary. For the crown glass-air boundary, the critical angle is 41.1 degrees.