Question

An unpolarised light beam strikes a glass surface at Brewster's angle. Then

• A. The reflected light will be partially polarised.
• B. The refracted light will be completely polarised.
• C. Both the reflected and refracted light will be completely polarised.
• D. The reflected light will be completely polarised but the refracted light will be partially polarised.

Answer 1

Answer: (D)

The reflected light will be completely polarised but the refracted light will be partially polarised.

Answer 2

At Brewster’s angle, the reflected light becomes completely polarised perpendicular to the plane of incidence. This happens because the angle between the reflected and refracted rays becomes $90\degree$ . The refracted light, however, remains partially polarised because it contains components of both polarisation states.