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प्रश्न
For an object placed at a distance 20 cm in front of a convex lens, the image is at a distance 20 cm behind the lens. The focal length of the convex lens is ______.
विकल्प
20 cm
10 cm
15 cm
40 cm
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उत्तर
For an object placed at a distance 20 cm in front of a convex lens, the image is at a distance 20 cm behind the lens. The focal length of the convex lens is 10 cm.
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संबंधित प्रश्न
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