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What must be the distance between an object and a converging lens of focal length 20cm ...

What must be the distance between an object and a converging lens of focal length 20cm to produce an erect image two times the object height?
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  • A 20cm
  • B 15cm
  • C 10cm
  • D 5cm
Correct Answer: Option C
Explanation:
F = \(\frac{uv}{u + v}\); v = 2u
20 = \(\frac{ux - 2u}{u + (-2u)}\); u = 10cm

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