Two rays traveling parallel to the principal axis strike a l

Two rays traveling parallel to the principal axis strike a large plano-convex lens having a refractive index of 1.56 (see figure below). 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 = 22.0 cm and the two rays are at distances h₁ = 0.500 cm and h₂ = 11.7 cm from the principal axis. Find the difference ?x in the positions where each crosses the principal axis.

Solution

Image formation does not depend upon height of object so the image will be formed at same point so x=0