A farsighted boy has a near point at 2.3 m and requires contact lenses to correct his vision to the normal near point. What is the correct choice of lens power for the contact lenses?
A) +3.6 diopters
B) +0.28 diopters
C) -0.28 diopters
D) +1.8 diopters
E) -3.6 diopters

Question

Quizplus · Accepted Answer

The lens power needed is calculated using the formula for lens power: P = 1/f, where f is the focal length in meters. The boy's near point is 2.3 m, and the normal near point is 0.25 m. The lens should bring the near point from 2.3 m to 0.25 m. The lens power required is P = 1/0.25 - 1/2.3 = 4 - 0.4348 = 3.5652 diopters, which rounds to +3.6 diopters.

A Farsighted Boy Has a near Point at 2