Magnification of an image is defined as the ratio of the height of image to the height of object.

Magnification (m) =

In the figure above by geometry we can easily see that ΔABO and ΔA’B’O’ are similar.

∴ …………… (1)

From definition of magnification.

Magnification (m) =

⇒ ……… (2)

From (1) and (2)

Magnification = which is the formula for magnification of lens.