A convex lens has a focal length of 15 cm. At what distance should an object be placed in front of the lens to get a real image of the same size of the object?

  1. A. 15 cm
  2. B. 10 cm
  3. C. 30 cm
  4. D. 40 cm

Correct Answer: C. 30 cm

Explanation

To obtain a real, inverted image of the same size as the object with a convex lens, the object must be placed at 2f. Here, f = 15 cm, so 2f = 30 cm.

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