A biconvex thin lens of refractive index μ2 =1.4 has a radii of curvature R1 = 20 cm and R2 = 60 cm, μ1 = 1.5 and μ3 =1.2 . Focal lengths are f1 and f2 in both the media
(a) The lens behaves as a concave lens
(b) f1 = f2
(c) f1 ≠ f2
(d) The lens behaves as a convex lens