- #1

maniacp08

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**Lenses/Images -- Find final image**

Two converging lenses, each having a focal length equal to 8 cm, are separated by 35 cm. An object is 30 cm to the left of the first lens.

**(a) Find the position of the final image using both a ray diagram and the thin-lens equation**

**(c) What is the overall lateral magnification?**

What I did:

s1' = f1s1/(s1-f1)

s1' = (8cm)(35cm)/(35cm-8cm) = 10.37cm

m1 = - s1'/s = -10.37cm/35cm = -.296285cm

s2' = f2s2/(s2-f2)

s2 = 35cm-30cm = 5cm

s2' = (8cm)(5cm)/(5cm-8cm) = -13.333cm

m2 = - s2'/s = - (-13.333cm)/5cm = 2.666cm

For question a isn't it 35cm+s1'+s2'=32.04cm or 32cm? This answer was marked wrong can anyone tell me what I did wrong?

For question c - m = m1*m2 = -.296285cm*2.666cm = -.78989581cm but this is again wrong

Please help, thanks!