Question

A double convex lens is made of a glass of refractive index 1·55, with both faces of the same radius of curvature. Find the radius of curvature required, if the focal length is 20 cm.

Answer 1

the radius of curvature of the given convex lens is 22cm

Answer 2

Hey !!

1/f = [ μ₂ - μ₁  - ] [1/R₁ - 1/R₂]

   = 1/20 = [ μ₂ - μ₁ ] 2/R

   = R = (20 × 1.10) cm

   = -22 cm

GOOD LUCK !!