Question: Double convex lenses are to be manufactured form a glass of refractive index 1.55, With both faces o...

Question

Double convex lenses are to be manufactured form a glass of refractive index 1.55, With both faces of same radius of curvature. What is the radius of curvature required it the focal length is :

Answer 1

Solution

: Lens maker formula.

$\frac { 1 } { \mathrm { f } } = ( \mu - 1 ) \left( \frac { 1 } { \mathrm { R } _ { 1 } } - \frac { 1 } { \mathrm { R } _ { 2 } } \right)$

Here, $\mathrm { f } = 20 \mathrm {~cm} , \mu = 1.55 , \mathrm { R } _ { 1 } = \mathrm { R }$ and