Question

Assuming the person wears contacts, what power of contact lens must be used to correct the vision of a farsighted person whose near point is 45.0 m? (no one would actually wear these as contacts)

Answer 1

Answer:

1.78 D

Explanation:

v = 25 cm

u = 45 cm

use lens equation

1 / f = 1 / v - 1 / u

1 / f  = 1 / 25 - 1 / 45

1 / f = (45 - 25) / 25 x 45

1 / f = 20 / 25 x 45

Power, P = 100 / f (m)  

P = 2000 / 25 x 45 = 1.78 D

Thus, the power of lens is 1.78 D.