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Two thin lenses of focal lengths 20 cm and 25 cm are placed in contact. The effection power of the combination is:

Options

  1. A45 dioptres
  2. B9 dioptres
  3. C1 9 dioptres
  4. D6 dioptres

Correct answer

B. 9 dioptres

Step-by-step solution

The correct answer is option B.

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