Question:
The radius of curvature of a concave mirror of focal length 20 cm is:
The radius of curvature of a concave mirror of focal length 20 cm is:
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For any spherical mirror, the radius of curvature (\( R \)) is always twice the focal length (\( f \)), i.e., \( R = 2f \).
Updated On: Oct 28, 2025
- 15 cm
- 10 cm
- 40 cm
- 60 cm
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the relationship between focal length and radius of curvature.
The radius of curvature (\( R \)) and the focal length (\( f \)) of a concave mirror are related by:
\[
R = 2f
\]
Step 2: Calculating the radius of curvature. Given \( f = 20 \) cm, \[ R = 2 \times 20 = 40 \text{ cm} \]
Step 3: Explanation of incorrect options.
- 15 cm, 10 cm, 60 cm are incorrect as they do not follow the formula \( R = 2f \).
Step 2: Calculating the radius of curvature. Given \( f = 20 \) cm, \[ R = 2 \times 20 = 40 \text{ cm} \]
Step 3: Explanation of incorrect options.
- 15 cm, 10 cm, 60 cm are incorrect as they do not follow the formula \( R = 2f \).
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