A magnification of 1 (plus or minus) means that the image is the same size as the object. If m has a magnitude greater than 1 the image is larger than the object, and an m with a magnitude less than 1 means the image is smaller than the object.

What is meant by magnification 1?

Size of Image / Size of object = 1. Size of image = Size of object. Also, the magnification is positive, Hence, the image formed is virtual and erect. Thus, Magnification of +1 means that image is virtual, erect and of the same size as that of the object.

Which mirror has a magnification of 1?

both concave and plane mirror.