An eye has a near-point at 125 cm.What focal length contact lens will be needed to move the near-point to 25 cm?

Question

Quizplus · Accepted Answer

We can use the lens formula, 1/f = 1/v - 1/u, where u is the object distance (125 cm) and v is the image distance (25 cm).
Plugging in the values, we get:
1/f = 1/25 - 1/125
1/f = 0.04
f = 1/0.04 = 25 cm
Therefore, the focal length of the contact lens needed is +31 cm (since it is a converging lens).

An Eye Has a Near-Point at 125 Cm