A man can see the objects upto a distance of one metre from his eyes. For correcting his eye sight so that he can see an object at infinity, he requires a lens whose power is

Options

A. `+ 0.5 D`
B. `+1.0 D`
C. `+ 2.0 D`
D. `-1.0 D`

Answer

D

Explanation

The image of object at infinity should be formed at `100cm` from the eye
`(1)/(f)=(1)/(oo)-(1)/(100)= -(1)/(100)`
So the power `=(-100)/(100)=-1D`
(Distance is given in `cm` but `P=(1)/(f)` in metres)