Question

where should we keep an object,in front of a concave mirror,so as to get a virtual and magnified image of it

Answer 1

concave mirror focal pole

Answer 2

In short, when an object is kept outside the centre of curvature (C) i.e. in between infinity and centre of curvature, the image formed is real, inverted and dimished and in between C and F (focus). You can easily figure this out by drawing the diagram yourself by using the law light follows when reflected by a curved surface.