Question

Power of the lens is -40, its focal length is
a. 4m
b. -40m
c. -0.25m
d. -25m​

Answer 1

Power of a lens is the reciprocal of focal length therefore the focal length of the above mentioned lens is 1÷power that is -1÷40 that is -0.025 . Though there is no option that has the answer.

Hope it was helpful. ☺