At what distance from a concave mirror of focal length 25 cm should an object be placed so that the size of the image is equal to the size of the object?
50 cm
When the object is placed at C, an image of equal size is formed at C but is inverted.
It is given that f = 25 cm.
C = 2f
∴ C = 50 cm.
Thus, when the object is placed at C, an inverted image of the same size is formed at C as well.
Hence, the object must be placed at a distance of 50cm from the concave mirror.