Question

what do you mean by power of a lens? what is the sl unit of the power of a lens? calculate the power of a concave lens of focal length 25 cm.
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Answer 1

Explanation:

calculate the power of a concave lens of a focal length 25 cm.the si unit of the power of focal of lens this is mean by 25 cm of lens this is a answer

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Answer 2

Answer:

Power of lens

(a) Meaning:

The reciprocal of the focal length of the lens is called its power of lens.

(b) S.I unit:

Its S.I unit is dioptre and it is denoted by symbol 'D'.

As the value of 'D' denotes the power of the lens, the value of 'f' denotes the focal length.

It is mathematically represented as 1 D = 1 m^{-1}1m

−1

.

(c) Power of the lens calculation:

Given:

Focal length of convex lens = 25 cm = 0.25 m

Focal length of concave lens = 10 cm = 0.1 m

Calculation:

To find the power of a lens with the given combination, the power of both the lens must be calculated individually.

please see the calculation in the picture