Jill is farsighted and cannot see objects clearly that are closer to the eye than 80.0 cm. What is the focal length of the contact lenses that will enable her to see objects at a distance of 25.0 cm from her eyes?
A) +36.4 cm
B) -36.4 cm
C) -21.2 cm
D) +21.2 cm
E) +32.5 cm

Question

Quizplus · Accepted Answer

To correct farsightedness, the lens must bring the near point to 25.0 cm. Using the lens formula 1/f = 1/v - 1/u, where v = 25.0 cm and u = -80.0 cm, we find f = +36.4 cm.

Jill Is Farsighted and Cannot See Objects Clearly That Are