A machinist with normal vision has a near point at 25 cm.The machinist wears eyeglasses in order to do close work.The power of the lenses is +1.75 diopters.With these eyeglasses,what is the near point of the machinist?
A) 17 cm
B) 14 cm
C) 10 cm
D) 21 cm
E) 24 cm

Question

Quizplus · Accepted Answer

The power of the lenses is given by the formula P = 1/f, where f is the focal length in meters. For +1.75 diopters, f = 1/1.75 = 0.571 meters or 57.1 cm. The new near point is calculated using the formula 1/f = 1/do + 1/di, where do is the object distance (near point with glasses) and di is the image distance (original near point without glasses, 25 cm). Solving for do gives approximately 17 cm.

A Machinist with Normal Vision Has a near Point at 25