Question

The power of a lens is 2.5D . What is the focal length in cm

Answer 1

Answer:

1/f =2.5D

f = 1/2.5×100

40cm

Answer 2

Answer:

Power = +2.5 D

F = 1/P = 1/2.5 = 0.4m = +40cm

Focal length is 40cm and it is a convex lens.

hope it helps! :)