Find the lateral magnification produced by the combination of lenses shown in Figure.

Explanation

If lenses are placed in contact, the focal length of single equivalent length can be given as
`(1)/(f)=(1)/(f_(1))+(1)/(f_(2))=(1)/(10)-(1)/(20)=(1)/(20)`
`rArr f=+20`
Now using lens formula considering system of lenses as a single lens, we get
`(1)/(v)-(1)/(u)=(1)/(f)`
`:. (1)/(v)=(1)/(-10)=(1)/(20)`
`(1)/(v)=(1)/(20)-(1)/(10)=(-1)/(20)rArrv=-20cm`
Now using magnification formula, we get
`m=(-20)/(-10)=2`