Question

power of a lens is -1.50.find the focal length

Answer 1

d=1/f

-1.50=1/f

f=-1/-1.50

Answer 2

Power of Len = 1 / focal length

= 1 / 1.5

= 0.666 cm

= 0.7 cm

Or

70 D

And - sign indicates concave len