If an object is placed at the focus of a convex lens, its image is

  1. A. at the focus on the same side.
  2. B. at the focus on the opposite side.
  3. C. coincident with the lens.
  4. D. at infinity.

Correct Answer: D. at infinity.

Explanation

When an object is placed exactly at the principal focus of a convex lens, the refracted rays emerge parallel to each other, forming a real, inverted, and highly enlarged image at infinity.

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