If the image formed by a spherical mirror is virtual, then the magnification value is Positive.
The reflecting surface of a spherical mirror may be curved inwards or outwards.
A spherical mirror, whose reflecting surface is curved inwards, that is, faces towards the center of the sphere, is called a concave mirror.
A spherical mirror whose reflecting surface is curved outwards is called a convex mirror.
The center of the reflecting surface of a spherical mirror is a point called the pole. It lies on the surface of the mirror. The pole is usually represented by
the letter P.
If the image formed by a spherical mirror is virtual, then the magnification value is positive.
Magnification produced by a spherical mirror gives the relative extent to which the image of an object is magnified with respect to the object size.
It is expressed as the ratio of the height of the image to the height of the object. It is usually represented by the letter m. If h is the height of the object
and h′ is the height of the image, then the magnification m produced by a spherical mirror is given by
m =
m =
The magnification (m) is also related to the object distance (u) and image distance (v). It can be expressed as Magnification (m) =
You may note that the height of the object is taken to be positive as the object is usually placed above the principal axis. The height of the image
should be taken as positive for virtual images.
However, it is to be taken as negative for real images. A negative sign in the value of the magnification indicates that the image is real. A positive
sign in the value of the magnification indicates that the image is virtual.