Question

the power of the lens with a focal length 20 cm is......​

Answer 1

P=1/f

P=1/20

P=0.05 dioptre

Answer 2

Here is your answer

Given,

f= 20 cm

=20/100 m

= 0.2 m

P= 1/f

 = 1/0.2 D

 = 5 D

Since, nature of lens is not given

If it is convex, P= +5 D

If it is concave, P= -5 D

HOPE IT IS USEFUL