Question

difference between a plane mirror convex mirror and concave mirror according to magnification

Answer 1

the reflecting surface is curved in ward is called concave mirror.
the reflecting surface is curved out ward is called convex mirror

Answer 2

plane mirror has erect image and of the size as the object.so, the maginfication is 1. while in convex and concave mirror, the magnification depends on the distance of object from the mirror and the focal length.
the magnification of convex and concave mirror is (f/f-u). where f is focal length and u is the distance of the object.