Question:
The focal length of a converging lens is 20 cm. The power of this lens will be
The focal length of a converging lens is 20 cm. The power of this lens will be
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The power of a lens is calculated using \( P = \frac{100}{f} \), where \( f \) is in cm. A convex lens has a positive power.
Updated On: Nov 5, 2025
- +0.2 D
- -0.2 D
- +5.0 D
- -5.0 D
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The Correct Option is C
Solution and Explanation
The power of a lens is given by the formula:
\[
P = \frac{100}{f}
\]
where \( f \) is the focal length in cm. Given \( f = 20 \) cm:
\[
P = \frac{100}{20} = 5D
\]
Since it is a converging (convex) lens, the power is positive.
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