When we have two convex lenses in contact we have the combination behaving as a converging lens. Can someone please give an analytical description for the combination of two concave lenses in contact with ray diagrams.


1 Answer 1


I know you asked for an analytical description, and ray diagrams, but seeing as this is homework related, I'd urge you to try the ray-tracing yourself and I think you'll find the answer without too much trouble. My suggestion would be to try and track how a couple significant rays move through your lens setup. For example, you might try one ray that passes above the center of the lens, one that passes directly through the center of the lens, and one that passes below it.

If you're struggling with this, try simplifying your problem a bit (maybe limit it to one concave lens to start) and then work your way back up to the question you're trying to find an answer to. Let me know how this goes.

  • $\begingroup$ I am getting something like this.the first lens will diverge the light rays nd these rays appear to be coming from its focus.now this will serve as a virtual object for the second lens.the second less will also diverge the light rays nd these will also appear to come from a point on the side of the object nd this might b our final image. $\endgroup$
    – deep joshi
    May 27, 2015 at 16:39
  • $\begingroup$ I'm not sure which side of the object you're referring to, but it sounds like you've got it under control :) $\endgroup$
    – hobenkr
    May 27, 2015 at 16:54

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