Suppose the distance from the lens system of the eye (cornea + lens) to the retina is 18 mm.
(a) What must the power of the lens be when looking at distant objects?
(b) What must the power of the lens be when looking at an object 20.0 cm from the eye?
(c) Suppose that the eye is farsighted; the person cannot see clearly objects that are closer than 1.0 m. Find the power of the contact lens you would prescribe so that objects as close as 20.0 cm can be seen clearly.