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A Concave lens of focal length `20 cm` produces an image half in size of the focal object. The distance of the real object isA. `20cm`B. `30 cm`C. `10 cm`D. `60 cm` |
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Answer» Correct Answer - A `m=(f)/(f+u)` `(1)/(2)=(-20)/(-20+u)` or `-20+u=-40` or `u=-40 +20` or `u=-20cm`. 10cm
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