Problem 35.3: Hidden lenses, point sources

Object A: Restart

Object B: Restart

Object C: Restart

Object D: Restart

Please wait for the animation to completely load.

Four lenses are represented by vertical lines. You can drag the light sources to any location (position is given in meters). Rank the lenses in terms of their focal lengths, from smallest to largest (most negative to most positive).

Problem authored by Melissa Dancy.