A farsighted person cannot see clearly objects that are closer to her eyes than 60.0 cm. Which one of the following combinations represents the correct focal length and the refractive power of the
Contact lenses that will enable her to comfortably see the objects at a distance of 25.0 cm from her
Eyes?
A) $- 42.9 \mathrm {~cm} , + 2.33$ diopters
B) $- 42.9 \mathrm {~cm} , - 2.33$ diopters
C) $+ 42.9 \mathrm {~cm} , + 2.33$ diopters
D) $+ 60 \mathrm {~cm} , + 42.9$ diopters
E) $+ 42.9 \mathrm {~cm} , - 2.33$ diopters

Question

A farsighted person cannot see clearly objects that are closer to her eyes than 60.0 cm. Which one of the following combinations represents the correct focal length and the refractive power of the
Contact lenses that will enable her to comfortably see the objects at a distance of 25.0 cm from her
Eyes? 
A) $- 42.9 \mathrm {~cm} , + 2.33$ diopters
B) $- 42.9 \mathrm {~cm} , - 2.33$ diopters
C) $+ 42.9 \mathrm {~cm} , + 2.33$ diopters
D) $+ 60 \mathrm {~cm} , + 42.9$ diopters
E) $+ 42.9 \mathrm {~cm} , - 2.33$ diopters

Quizplus · Accepted Answer

The focal length needed is positive because the lens must converge light to correct farsightedness. Using the lens formula, the focal length is calculated to be approximately +42.9 cm, which corresponds to a refractive power of +2.33 diopters.

A Farsighted Person Cannot See Clearly Objects That Are Closer −42.9 cm,+2.33- 42.9 \mathrm {~cm} , + 2.33−42.9 cm,+2.33

A Farsighted Person Cannot See Clearly Objects That Are Closer $- 42.9 \mathrm {~cm} , + 2.33$