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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.
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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