hey- i've been working on this one for quite some time now and just cant seem to get it:(adsbygoogle = window.adsbygoogle || []).push({});

Two converging lenses with focal lengths 10 cm and 20 cm are placed 30 cm apart. Rays from a very distant object are impinged on the lens system parallel to the principal axis.

What is the refractive power of the combination of these two lenses?

it offers this help:

Look at your ray diagram. Suppose you replaced the two-lens combination with one lens that focused the incoming parallel rays the same distance away. The focal length f of the replacement lens is how far away it focuses incoming parallel rays, and the refractive power is 1/f !

i have tried everything i know how to with the given numbers...

thank you for your help!!!

-shawna

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# Homework Help: Two Lenses

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