Correct Answer - Option 2 :
\(tan^{-1}(\frac{3}{2})\)
Concept:
Brewster’s Angle: Brewster's angle is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection.
\(tan{\theta _i} = \sqrt {\frac{{{\epsilon_2}}}{{{\epsilon_1}}}} \)----(1)
Calculation:
For no reflection incident wave should be completely transmitted to another medium at Brewster angle.
Given:
ϵ2 = 9, ϵ1 = 4
From equation (1) we get,
\(tan{\theta _i} = \sqrt {\frac{9}{4}} \)
\({\theta _i} = {\tan ^{ - 1}}\frac{3}{2}\)
Note: Brewster angle does not affect S polarized waves.