For a concave mirror,when is the object distance equal to the image distance?

Question

Quizplus · Accepted Answer

When the object is placed at a distance that is twice the focal length of the concave mirror, the image is formed at a distance that is equal to the object distance. This is in accordance with the mirror formula: 1/f = 1/do + 1/di, where f is the focal length, do is the object distance, and di is the image distance. When do = 2f, then di = do, and hence the option C is the correct answer.

For a Concave Mirror,when Is the Object Distance Equal to the Image