Question

doctor advised to use 2D lens what is the focal length of it

Answer 1

Hello dear friend!!
Rajdeep here...

Power of the lens is 2D (Dioptre).

We know, Power is the reciprocal of focal length in metres.

P = 1/f
=> 2 = 1/f
=> f = 1/2 m
So the focal length is 0.5m

Thanks..

Answer 2

Heya !!!

This is Your Answer.

Given Focal Length is 2 D.

We know that ...
P = 1/f(in m)
2 = 1/f
f = 1/2
F = 0.5 m.
= 50 cm.
Hence, it will be a convex lens of focal length 50 cm .

Hope It Helps