Question

The near point for a person's eye is 85.0 cm. To see objects held as closely as 25.0 cm from the eye, what power contact lenses should be worn?

Answer 1

2.82 D

Step-by-step explanation:

Near point of the person eye is 85 cm that is
`u=85\ cm`

He wants to see the object at 25 cm so
`v=25\ cm`

For the lens we know that
`(1)/(f)=(1)/(v)-(1)/(u)`

`(1)/(f)=(1)/(25)-(1)/(85)`

\frac{1}{f}=0.04-0.01170=0.02823

`f=35.41\ cm`

We know that power of the lens
`P=(1)/(f\ in\ meter)`

So
`P=(1)/(0.3541)=2.8235\ D`