(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A compound lens system consists of two converging lenses, one at x= -20cm with focal length f_{1}= +10cm, and the other at x= +20cm with focal length f_{2}= +8cm . An object 1 centimeter tall is placed at x = -50cm.

What is the location of the final image produced by the compound lens system? Give the x coordinate of the image.

2. Relevant equations

1/f = 1/s' + 1/s

m = y'/y = -(s'/s)

3. The attempt at a solution

I am not sure. I believe I need to do the first equation I posted twice. Using the s' from the first lense as the s (object) for the second lens.

for lens 1 i get:

1/f = 1/s' + 1's

1/10 = 1/s' + 1/-30 (used negative since it is on oppostie side of mirror?)

s' = 7.5 cm (is that telling me it is 7.5 from the lens correct? so in between the lens and the f.)

for lens 2 i get:

1/f = 1/s' + 1/s

1/8 = 1/s' + 1/-7.5 (used negative since it is on oppostie side of mirror?)

s' = 3.87 cm (is that telling me it is 3.87 from the lens correct? so in between the lens and the f.)

if these are corect it is telling me the final image is located at x = + 23.87 but that is wrong.

so where did i go wrong in my calculations?

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# Homework Help: Two Lens System - Image

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