College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 3

A person sees clearly wearing eyeglasses that have a power of 4.00 diopters when the lenses are 2.00 cm in front of the eyes. (a) What is the focal length of the lens (b) Is the person nearsighted or farsighted (c) If the person wants to switch to contact lenses placed directly on the eyes, what lens power should be prescribed