Question

The power of a lens is 2.5 dioptre. What is the focal length and the type of lens

Answer 1

power=1/focal length
focal length =1/power of lens
f=1/2.5
f=10/25
f=0.4
the lens is convex lens

Answer 2

Given :

The power of a lens , P = 2.5 dioptre .

To Find :

The focal length and the type of lens .

Solution :

We know , focal length is given by :

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

Putting all given values we get :

$f=\dfrac{1}{2.5}\\\\f=0.4 \ m =40\ cm$

Now , we can see that the focal length is positive .

Therefore , it is a convex lens .

Learn More :

Lens and power

https://brainly.in/question/12318028