Define power of a lens. What is its common unit?

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Solution

The power of the lens is a measure of its degree of convergence or divergence.
The power of a lens is also defined as the inverse of its focal length measured in meters, that is, $P o w e r o f l e n s = \frac{1}{f o c a l l e n g t h o f t h e l e n s}$ .
It is measured in dioptres $(D)$ .
One dioptre is equal to one $m^{- 1}$ .

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Define power of a lens. What is its common unit?

The power of the lens is a measure of its degree of convergence or divergence.The power of a lens is also defined as the inverse of its focal length measured in meters, that is, Poweroflens=1focallengthofthelens.It is measured in dioptres D.One dioptre is equal to one m-1.