physics
posted by Jim .
The nearpoint of an eye is 123 cm. A corrective lens is to be used to allow this eye to clearly focus on objects 25 cm in front of it.
What should be the focal point of this lens?

B)
What is the power of the needed corrective
lens? 
A prescription for a corrective lens calls for +2.50 D. The lensmaker grinds the lens from a “blank” with n=1.56 and a performed convex front surface of radius of curvature of 20.0 cm. What should be the radius of curvature of the other surface

A prescription for a corrective lens calls for +2.50 D. The lensmaker grinds the lens from a “blank” with n=1.56 and a performed convex front surface of radius of curvature of 20.0 cm. What should be the radius of curvature of the other surface?