An optical system consists of two convergent lenses with focal length `f_1=20 cm and f_2=10 cm.` The distance between the lenses is `d=30 cm.` An object is placed at a distance of `30 cm` from the first lens. At what distance from the second lens will the images be obtained ?

Answer

C

Explanation

For `L_1,`
`1/v-((1)/-30)=1/(+20)`
`:. v=+60 cm`
For `L_2`,
`1/v-(1)/(+30)=1/(+10)`
`:. v=+7.5 cm`