A woman has been prescribed lenses that have a +3.2-diopter refractive power. The glasses are worn 2.0 cm from her eyes.

Question

A woman has been prescribed 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

Please explain your answer

Answer 1

Hi

Find f

P= 1/f

f= 1/3.2 =0.3125 m =31.25 cm

d_o= 25- 2= 23 cm

use the lens equation

1/f =1/d_o+ 1/d_i

_{plug in to find} di

Read your book to know which lens you can use to correct eye defect , when we use

the positive power lens .