# Mirror Formula And Magnification

In a Spherical Mirror,
The distance of the object from its pole is called the Object distance (u).
The distance of the Image from the Pole of the Mirror is called the Image distance (v).
The Distance of the principal focus from the pole of the mirror is called the Focal length (f).

There is a relationship between these three quantities given by the mirror formula,

-------------------------------------(10.1)
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Magnification:
It can be defined as the ratio of the height of the image to the height of the object. It is usually represented by the letter m.
Height of the image (hâ€™)

m =Height of the object (h)-------------------------------------(10.2)

Magnification can be related to object distance (u) and the image distance (v). It can be expressed as

Magnification (m)= --------------------------------------------(10.3)

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.Â