Question

where do we got an image of an object, when placed at centre of curvature of a concave mirror

Answer 1

When the object AB is placed at the centre of curvature C, then a ray of light AD which is parallel to the principal axis and another ray AE which pass through the principal focus intersect each other after reflection at point A’ just below the position of the object. Thus the image formed in this case is at the centre of curvature, of same size as the object, real and inverted.