What is meant by magnification? Write its expression. What is its sign for real image and virtual image?

Explanation

Magnification produced by a spherical mirror gives how many times the image of an object is magnified with respect to the object size.
It can be defined as the ratio of the height of the image `(h_i)` to the height of the object `(h_o)`.
Magnification `= m = ("height of the image")/("height of object")`
(a) for real image it is negative.
(b) for virtual image it is positive.