Question

the power of a lens is 2.5d.the focal length and the nature of lens will be

Answer 1

focal length =1/D
=1/2.5m
=0.4m
=40cm
focal length of lens is 40cm and it is convex lens . so nature of lens is converging.
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Answer 2

Given:

The power of a lens=2.5 d

To find:

The focal length and the nature of the lens

Solution:

The focal length of the lens is 0.4m and it is convex in nature.

We can find the focal length by taking the steps mentioned below-

We know that the power of a lens is obtained by taking the reciprocal of its focal length.

The power of the lens=2.5 d

Let the focal length of the lens be f.

Power, D=1/focal length of the length

D=1/f

On putting the values, we get

2.5=1/f

f=1/2.5

f=10/25

f=2/5

f=0.4

So, the focal length of the lens is 0.4 meters.

The nature of a lens depends on the power and focal length.

here, both the power and the focal length are positive.

The lens is convex and it will form real and inverted images.

Therefore, the focal length of the lens is 0.4m and it is convex in nature.