What will be the focal length of a lens whose power is given as `+ 2.0 D ?`

The focal length of a lens of power + 4D is :

What is focal length of a lens of power 2.5 D ?

The focal length of a lens with power 2.5 D is …………………..

Find the focal length of a lens having -0.5 D power.

Doctor has prescribed a lens having power +2 D . What will be the focal length of the lens ? What is the type of the lens and what must be the defect of vision ?

The focal length of a concave lens with power -4D is ……………….