A converging lens has focal length of 50 mm. What is the power of the lens?

Given: 

Focal length, $f$ = $+$50 mm = $+$0.05 m  $(\because lens\ is\ converging\ in\ nature,\ focal\ length\ will\ be\ positive)$

To find: ​​Power of a lens, $P$.

Solution:

We know that power of the lens is given by-

$Power\ (P)=\frac {1}{f}$

Substituting the given value we get-

 $P=\frac {1}{0.05}$

 $P=\frac {100}{5}$

 $P=+20D$

Hence, the power of the lens is 20 D.

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Updated on: 10-Oct-2022

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