Optics question, can anyone confirm my answer?

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SUMMARY

The discussion centers on a physics problem involving two converging lenses with a focal length of 27 cm, placed 16.5 cm apart. The object is positioned 35 cm in front of the first lens, resulting in a calculated image distance (di1) of 118.125 cm from the first lens and a second image distance (di2) of 21.33 cm from the second lens. The total magnification (Mt) is computed as 0.785X, but there are discrepancies in the magnification signs that need clarification. Participants confirm the calculations for di2 while suggesting a reevaluation of the magnification values.

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  • Understanding of lens equations, specifically 1/f = 1/di + 1/do
  • Knowledge of magnification formula M = -di/do
  • Familiarity with the concept of object and image distances in optics
  • Basic grasp of converging lens behavior and focal lengths
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  • Review the derivation of the lens formula and its applications in optics
  • Study the principles of total magnification in multi-lens systems
  • Explore the impact of sign conventions on image distance and magnification
  • Practice solving similar problems involving multiple lenses and varying object distances
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Homework Statement


Two converging lenses of focal length=27cm are placed 16.5cm apart. If an object is placed 35cm in front of the first lens, where will the final image be produced? What will be the total magnification?


Homework Equations


1/f=1/di+1/do
do2=D-di1
M=-di/do

The Attempt at a Solution


1/f1=1/di1+1/do1
1/27=1/35+1/di1
di1=118.125cm

do2=D-di1
do2=16.5-116.125
do2=-101.625cm

1/f2=1/do2+1/di2
1/27=1/-101.625+1/di2
di2=21.33cm<<<<<

Mt=M1M2=(-21.33/-101.626)(118.125/35)=0.785X<<<<<


If something is wrong, please show me my mistake, and if it's right please let me know!
 
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It_Angel said:

Homework Statement


Two converging lenses of focal length=27cm are placed 16.5cm apart. If an object is placed 35cm in front of the first lens, where will the final image be produced? What will be the total magnification?

Homework Equations


1/f=1/di+1/do
do2=D-di1
M=-di/do

The Attempt at a Solution


1/f1=1/di1+1/do1
1/27=1/35+1/di1
di1=118.125cm

do2=D-di1
do2=16.5-116.125
do2=-101.625cm

1/f2=1/do2+1/di2
1/27=1/-101.625+1/di2
di2=21.33cm<<<<<

Mt=M1M2=(-21.33/-101.626)(118.125/35)=0.785X<<<<<If something is wrong, please show me my mistake, and if it's right please let me know!
I agree with your value of di2.

For the magnification, try calculating it again -- I agree with the values 21.33, 101.6, 118.1, and 35, but I get a different final answer.

Also -- again on the magnification -- is M1 positive or negative? How about M2? What does that make Mt?

Hope that helps.

p.s. Welcome to Physics Forums.
 
Thanks a lot :)
 

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