Question

The focal length of a convex lens is 25cm. What is its power?​

Answer 1

Answer:-

$\pink{\bigstar}$ Power of the lens is $\large\leadsto\boxed{\tt\purple{+4 \: D}}$

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• Given:-

• The focal of a convex lens is = 25cm = 0.25m

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• To Find:-

• Power of the lens

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• Solution:-

We know,

• The Power of the lens is inversely proportional to the focal length of the lens.

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$\blue{\bigstar}$ $\large\underline{\boxed{\bf\red{P = \dfrac{1}{f}}}}$

where,

• P = Power of the lens

• f = focal length of the lens

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Hence,

➪ $\sf P = \dfrac{1}{0.25}$

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➪ $\bf\green{P = 4 D}$

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★ Since, the lens is convex therefore positive sign.

Hence, the power of the lens is +4 D.

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✯ Here, D denotes the unit of the power of lens i.e Dioptre.