With unaided vision, a librarian can focus only on objects that lie at distances between 5.0 m and 0.50 m.
(a) Which type of lens (converging or diverging) is needed to correct his nearsightedness? Explain.
(b) Which type of lens will correct his farsightedness? Explain.
(c) Find the refractive power needed for each part of the bifocal eyeglass lenses that will give the librarian normal visual acuity from 25 cm out to infinity. (Assume the lenses rest 2.0 cm from his eyes.)