Concept:A concave mirror produces an image of the same size as the object when the object is placed at its centre of curvature.
Explanation:For a concave mirror, the centre of curvature
C is at a distance equal to the radius of curvature
R from the pole.
The focal length is
f, and for a concave mirror,
R=2f.
When the object is placed at
C, its distance from the mirror is
R.
Using the mirror formula or ray diagram, the image is formed at
C itself.
The magnification is
m=−1, so the image is inverted and exactly the same size as the object.
Thus, the correct position is the centre of curvature.
Answer:A. at the centre of curvature