A plano-convex lens is to have a focal length of 40 cm. It is made of glass of index of refraction 1.65. What radius of curvature is required?
A) 32. cm
B) 44. cm
C) 26. cm
D) 13. cm
E) 36. cm

Question

Quizplus · Accepted Answer

The lensmaker's equation for a plano-convex lens is 1/f = (n - 1)(1/R), where f is the focal length, n is the refractive index, and R is the radius of curvature. Solving for R with f = 40 cm and n = 1.65 gives R = 26 cm.

A Plano-Convex Lens Is to Have a Focal Length of 40