39. The Brewsters angle $i_b$ for an interface should be :

39. The Brewsters angle ib for an interface should be :

(a) \(30^\circ < i_B < 45^\circ\)

(b) \(45^\circ < i_B < 90^\circ\)

(c) \(i_B = 90^\circ\)

(d) \(0^\circ < i_B < 30^\circ\)

Answer :  (b) \(45^\circ < i_B < 90^\circ\)

\(\tan i_B = \mu\)

\(\mu > 1 \implies i_B > 45^\circ\)