American Board of Opticianry (ABO) Practice Test

Which type of lenses represent a biconvex lens?

1. cylinder lenses

2. plus lenses

3. minus lenses

4. two plus surfaces

The correct answer is: two plus surfaces

A biconvex lens is a type of lens that is curved outwards on both sides. In comparison, a cylinder lens only has one curved surface, while minus lenses are curved inward and do not have the outward convex shape. Plus lenses generally have a convex shape, but they are not necessarily biconvex. The only option that includes two outwardly curved surfaces, making it biconvex, is D two plus surfaces. Therefore, D is the correct answer.