When unpolarised light from air incidents on the surface of a medium of refractive index sqrt‌3, then the reflected light is totally polarised. The angle of refraction is
Step 1: Using Brewster's Law Brewster's law says that µ=tan‌ip, where µ is the refractive index of the medium, and ip is the polarising angle (angle of incidence for which the reflected light is completely polarised). We know the refractive index µ=√3. So, √3=tan‌ip. We know that tan‌60∘=√3. So, ip=60∘. Step 2: Finding the Angle of Refraction When light is totally polarised after reflection, the angle between the reflected and refracted rays is 90∘. So, ip+r=90∘, where r is the angle of refraction. This means r=90∘−ip. We already found ip=60∘, so r=90∘−60∘=30∘.