Obtain the equation of magnification of combination of lenses.

Explanation

Suppose `m_1`, and `m_2`, magnification o combination of two lenses are as shown in figure

As shown in the figure for convex lens L, object distance = OP = u
image distance = PI. = v. and PI = v
Similarly, for convex lens `I_2` object distance = PI.= v.
image distance = PI = v
From the figure,
For lens `L_1` magnification, `m_1 = (v.)/(u)` ... (1)
For lens `L_2` magnification, `m_2 = (v)/(v.)` ... (2)
Now magnification for the lens combination,
`m=v/u`
`therefore v/u=(v)/(v.)xx(v.)/(u)`
`therefore m=m_2xxm_1`
If a combination consists of more than two lenses,
`therefore m = m_1 xx m_2 xx m_3 .......... xx m_n`