A converging lens has a focal length of 50 cm. The power of this lens is :(a) +0.2D (b) −2.0D (c) +2.0D (d) −0.2D

(c) +2.0 D

Explanation

Given:

Focal length of the lens, $f$ = $+$50 cm = $+$0.50 m     $(\because lens\ is\ converging\ in\ nature,\ focal\ length\ will\ be\ positive)$

To find: Power of the lens, $P$.

Solution:

Power of a lens is given by-

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

Substituting the given values we get-

$P=\frac {1}{0.50}$

$P=\frac {100}{50}$

$P=+2D$

Thus, the power of the lens, $P$ is 2 D or 2.0 D. 

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Updated on: 10-Oct-2022

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