College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 53

Two rays traveling parallel to the principal axis strike a large plano-convex lens having a refractive index of 1.60 (Fig. P23.54). If the convex face is spherical, a ray near the edge does not pass through the focal point (spherical aberration occurs). Assume this face has a radius of curvature of R = 20.0 cm and the two rays are at distances h 1 = 0.500 cm and h 2 = 12.0 cm from the principal axis. Find the difference x in the positions where each crosses the principal axis.