1) Magnification = height of the image / height of the object = distance of the image / distance of the object
2) The magnification produced by a plane mirror is +1 means then the size of the image is equal to the size of the object.
3) + sign indicates that the image is erect.
.-. Magnification ' + 1' indicates the image is erect and size of the image is equal to size of the object.