- #1
chickenoodle
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Homework Statement
There are 2 lenses separated by 5 cm. Very far to the left of the first lens is an object (the distance of the object from lens one is NOT given). The focal length of lens 1 is 20 cm and the focal length of lens 2 is 10 cm. Where is the image due to the first lens? State the image's distance from lens 1 and whether this image is on the right of left of lens 1.
Homework Equations
the mirror equation:
1/s + 1/s' = 1/f
s is the distance of the object
s' is the distance of the image
f is the focal length
The Attempt at a Solution
for the first lens:
1/s' = 1/f - 1/s = (1/20cm) - 1/s
s is not given and I don't know how to find it so I used a crude method of setting up an equation with 2 unknown variables.
if d is the total distance; d = x + 5cm
then x is the distance between the object and lens 1; x = d - 5cm
so I set x = s = d - 5cm and then solved for s'.
s' = [(1/20cm) - {1/(x-5cm)}]^-1
This is the whole solution I came up with but you get the idea, the equation just gets longer and uglier.
this doesn't seem right. Is there some way to solve for s and get a numerical value?
This question is just part "a" from one very long question and I'm hoping that if someone can help me figure this first part out I'll be able to do the rest on my own.
Thanks