Question

Power
of the
the lens
lens is - 40 ets
focal length
is​

Answer 1

Answer:

p = 1 / f ( in meters)

- 40 = 1 / f

f = 1/-40

f = 25 cm

Answer 2

Answer:-

• Power of a lens =-40D
• P=-40D

Its a concave lens .

• Focal length=f=?

We know that

$\boxed{\sf P=\dfrac{1}{f}}$

$\\ \sf \longmapsto f=\dfrac{1}{P}$

$\\ \sf \longmapsto f=\dfrac{1}{-40}$

$\\ \sf \longmapsto f=.025m$

$\\ \sf \longmapsto f=2.5cm$