College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 45

If a typical eyeball is 2.00 cm long and has a pupil opening that can range from about 2.00 mm to 6.00 mm, what are (a) the focal length of the eye when it is focused on objects 1.00 m away, (b) the smallest f -number of the eye when it is focused on objects 1.00 m away, and (c) the largest f -number of the eye when it is focused on objects 1.00 m away