Mrs.McKay has been prescribed eyeglasses with lenses that have a +3.2-diopter refractive power.The glasses are worn 2.0 cm from her eyes.With the lenses,she can read a magazine held 25 cm from her eyes.Which one of the following statements is necessarily true? Note: The near points and far points given in the following answers are measured relative to her eye.
A)She has a far point of 3.2 m.
B)She has a far point of 0.25 m.
C)She has a near point of 3.2 m
D)She has a near point of 6.4 m.
E)She has a near point of 0.87 m.

Question

Quizplus · Accepted Answer

The lens formula (1/f = 1/v - 1/u) can be used to find the near point. With a lens power of +3.2 D and the object (magazine) at 25 cm, the near point is calculated to be approximately 0.87 m.

MrsMcKay Has Been Prescribed Eyeglasses with Lenses That Have a +3.2-Diopter