Question

A radii of curvature of two faces of a biconvex lens of refractive index 2:3 the focal length og lens is 12cm the radius of curvature of the surface with low value of radius of curvature

Answer 1

From left to right  1 1 L f = (µ – 1) 1 1 – – –2 R R       = (µ = 1) 1 1 – 2R R       µ concave surface R convex surface 2R 1 1 L f = –  –1 2 µ R From right to left  2 1 L f = (µ – 1) 1 1 – 2 ( ) R R         = (µ – 1) 1 1 – 2R R       = –  –1 2 µ R  1 1 L f = 2 1 L f = – 2 ( –1) R µ Option (B) and (D) are correct.