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

CBSE Class 10 CBSE Class 10 Science
,
1

Given that the power of lens P = 2D

We know that, P = 100 / f(cm)
2 = 100/f

  2f = 100

f = 100/2 = 50 cm

The focal length of the lens = 50 cm