Question

What is the focal length of double convex lens for which the radius of curvature of each surface is 50cm and the refractive index of glass is 1.50?

Answer 1

Use lens maker’s formula: (1/ f)=(n-1)[(1/R1)-(1/R2)] with n=1.50,R1=50cm and R2=-50 cm.
The result is :f=50cm.