Question

An object is 1.75 m to the left of a lens of focal length 0.94 m. A second lens of focal length -2.5 m is 0.62 m to the right of the first lens. Find the distance between the object and the final image formed by the second lens.

m   
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What is the overall magnification (with sign)?

Answer 1

See the refs. The key to this kind of problem is that the 1st (left) lens's
(intermediate) image is the 2nd (right) lens's object. Then using notation from ref. 1 (+uN is object distance to left of lens N and +vN is image distance to right of lens N), we have initially:
u1 = 1.75 m; f1 = 0.94 m; d= 0.62 m; f2 = -2.5 m; v2 = TBD
Solving,
v1 = 1/(1/f1-1/u1) = 2.03 m
u2 = d-v1 = -1.41m

v2 = 1/(1/f2-1/u2) = 3.23 m

A. Final Image location relative to object = v2+d+u1 = 5.60 m
B. Magnification = v1v2/(u1u2) = -2.66.

Hope this helps you.

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