Question

Suppose that you have farsighted eye such that your near point is 95 cm. As a result you need a reading a Whatlens power in D must you wear so that a newspaper can be read at a distance of 25 cm? Assume the lens is very close to your eye. COE LOE O 101 2.94

Answer 1

Given: Object distance, u = - 25 cm

Image distance, v = - 95 cm

So, focal length will be ,

$f = \frac{u*v}{u-v}$

f -25 * (-95) -25 + 95 475 -ст 14

Now to calculate power of lens,

$P= \frac{1}{f} = \frac{14}{475}*100 = 2.94 D$  _Ans.

(* 100 is multiplied to convert focal length from cm to meters)