Question

Doctor advised to use 2D lens.what is its focal length

Answer 1

Power=2D and we know p=1/f 
so, f=1/2=0.5m

Answer 2

Given:

Power,

= 2D

To Find:

Focal length = ?

Solution:

As we know,

⇒ $Power=\frac{1}{Focal \ length}$

⇒ $Focal \ length=\frac{1}{Power}$

On substituting the given value, we get

⇒                       $=\frac{1}{2}$

⇒                       $= 0.5 \ m$

Thus, the focal length will be "0.5 m".