A transparent thin film of uniform thickness and refractive index n = 1.4 is coated on the convex spherical surface of radius R at one end of a long solid glass cylinder of refractive index n = 1.5, as shown in the figure. Rays of light parallel to the axis of the cylinder traversing through the film from air to glass get focused at distance f from the film, while rays of light traversing from glass to air get focused at distance f from the film. Then (A) |f|= 3R (C) |f| = 2R (B) |f|= 2.8 R (D) |f| = 1.4 R n n