Concave mirror is a part of spherical mirror.
Magnification of a spherical mirror = m = f/(f-u)
Focal length of a mirror = f
The distance from focal point to the object is = p.
i) When the object is placed within the focus , then
u = -(f - p), f = f
Magnification of the mirror = m = size of image/size of object = -f/(-f+(f-p))=f/p .......(1)
ii) if the object placed beyond F at a distance P. So
u= -(f + p) = f = -f
Magnification of the mirror = f/(f-u) =-f/p ............(2)
(1)/(2) = h1 /h2 = (OJ x f/p)/(-OJ x f/p) = -1
