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Question
At what distance from a concave mirror of focal length 25 cm should an object be placed so that the size of image is equal to the size of the object.
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Solution
If an object is placed at the centre of curvature of a concave mirror, the size of the image is equal to the size of the object.
Given,
focal length = 25 cm
As, center of curvature = 2 × focal length
Therefore,
center of curvature
= 2 × 25
= 50 cm
Hence, the object should be placed at 50 cm.
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