College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 4

An elderly sailor is shipwrecked on a desert island, but manages to save his eyeglasses. The lens for one eye has a power of +1.20 diopters, and the other lens has a power of +9.00 diopters. (a) What is the magnifying power of the telescope he can construct with these lenses (b) How far apart are the lenses when the telescope is adjusted for minimum eyestrain