Question

if the power of lens is -40, its focal length is what?​

Answer 1

Answer:

focal length = - 25

I hope it will help u

Answer 2

Answer:

     -2.5cm

Explanation:

power of lens is -40

Since power is negative its a concave lens

Power = 1 / focal length

-40 = 1 / focal length

focal length = 1 / -40

focal length = -0.025m = -2.5cm