Chapter 25, Problem 12P

Range of the focal length of the eye. We can model the eye as a sphere 2.50 cm in diameter with a thin lens in the front and the retina along the back surface. A 20-year-old person should be able to focus on objects from her near point (see Table 25) up to Infinity. What is the range of the effective focal length of the lens of the eye for this person?

Table 25.1 Receding of near point with age

Age (years)	Near point (cm)
10	7
20	10
30	14
40	22
50	40
60	200