Question

A ray of light strikes a piece of glass at an angle of incidence of 60° and the reflected beam is completely plane polarised. The refractive index of glass is:

• A. \( \sqrt{2} \)
• B. \( \sqrt{3} \)
• C. \( \sqrt{5} \)
• D. \( \sqrt{3} \)

Hint:

At Brewster's angle, the angle of incidence leads to total polarization of the reflected light. Use the formula \( n = \tan(\theta_B) \) to find the refractive index.

Answer 1

The Correct Option is B

Step 1: Brewster’s angle. The angle of incidence at which light is completely polarized upon reflection is called Brewster’s angle. The refractive index of the medium can be found using: \[ \tan(\theta_B) = n \] Where \( \theta_B = 60^\circ \) and \( n \) is the refractive index.
Step 2: Conclusion. Thus, the refractive index \( n = \sqrt{3} \).