If a person has a near pt of 122cm, wears a contact lens with focal L of 37cm.?

Question

How close can she hold the newspaper to her eyes and still be able to read it?

Answer 1

e = focal length of eye lens,

r = distance from eye lens to retina,

u = closest distance for newspaper.

1 / 122 + 1 / r = 1 / e ...(1)

1 / u + 1 / r = 1 / e + 1 / 37 ...(2)

Subtracting (1) from (2):

1 / u - 1 / 122 = 1 / 37

u = 28.4 cm.