## Optics question, can anyone confirm my answer?

1. The problem statement, all variables and given/known data
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?

2. Relevant equations
1/f=1/di+1/do
do2=D-di1
M=-di/do

3. 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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 Quote by It_Angel 1. The problem statement, all variables and given/known data 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? 2. Relevant equations 1/f=1/di+1/do do2=D-di1 M=-di/do 3. 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 :)

 Tags 2 lens, converging lens, optics, physics