An object is placed `12 cm` to the left of a diverging lens of focal length `-6.0 cm.` A converging lens with a focal length of `12.0 cm` is placed at a distance d to the right of the diverging lens. Find the distance d that corresponds to a final image at infinity.

Explanation

Applying lens formula ` (1)/(v) - (1)/(u ) = (1)/(f) ` twice
we have ` (1)/(v_1) - (1 )/(-12) =(1)/(-6)`
`implies v_1 =- 4 cm and (1)/(oo) - (1)/(v_1 -d) = (1)/(12) implies d= 8 cm`