For a converging lens with two convex surfaces,the radius of curvature for both surfaces is 20 cm.If the focal length is 10 cm,what must the index of refraction be?
A) 1.5
B) 2.5
C) 2.0
D) 3.0

Question

Quizplus · Accepted Answer

For a lens with two convex surfaces, we have:
1/f = (n-1) * (1/R1 - 1/R2)
For this particular lens, R1 = R2 = 20 cm, and f = 10 cm.
Substituting these values, we get:
1/10 = (n-1) * (1/20 - 1/20)
Simplifying, we get: n = 2.0. Therefore, the correct choice is (C).

For a Converging Lens with Two Convex Surfaces,the Radius of Curvature