Question

A nearsighted person has a far point of 25.525.5cm and is prescribed contact lenses to correct her vision. What lens strength (a.k.a., lens power), in Diopters, should be prescribed

Answer 1

The right answer is "-3.90 D".

Step-by-step explanation:

According to the question,

Far point,

v = -25.525 cm

and,

u =
`\infty`

By using the lens formula, we get

⇒
`(1)/(f) =(1)/(v) -(1)/(u)`

On putting the values, we get

⇒
`=(1)/(-25.525) +(1)/(\infty)`

⇒
`f=-25.525 \ cm`

or,

⇒
`=-25.6 \ cm`

hence,

⇒
`Power (P)=(100)/(f)`

⇒
`=(100)/(-25.6)`

⇒
`=-3.90 \ D`