Question: Two rays travelling parallel to the principal axis strike a large plano-convex lens having a refract...

Question

Two rays travelling parallel to the principal axis strike a large plano-convex lens having a refractive index of 1.60. If the convex face is spherical, a ray near the edge does not pass through the focal point (spherical aberration). If this face has a radius of curvature of 20.0 cm & the two rays are h₁ = 0.5 cm & h₂ = 12.0 cm from the principal axis, find the difference in the positions where they cross the principal axis –

Answer 1

Solution

1.60 sin i = sin r

$\frac { 1.60 \times h } { R }$ = sin r

$\frac { \mathrm { h } } { \mathrm { PF } } = \tan ( \mathrm { r } - \mathrm { i } )$

in this way we can calculate PF for both rays and difference in position = PF₂ – PF₁