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Groundd
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My teacher assigned us 2 problems to do that were the exact same. One he wanted us to use the thin lenses equation, and the other he wanted us to use think lens equation. i need help becuase I don't know which one I am doing wrong and my answer is not lining up as it should, since they are the same problem, it should be the same solution. I think I am messing up on the thin lense beucase he worked out part of it out when he wanted us to use think lense
Find the effective focal length of the two lens system. The focal length of the first lens is 20 cm and the second lens is -20 cm with the separation between the two lens being 10 cm. Locate the principal planes. Locate the image of an object that is 1 m in front of the first lens. Express the location relative to the location of the second lens.
f1is 20cm
f2is -20
and the distance between the two is 10 cm
the object is 1m(100 cm) in front of the first lens
for thick lense the equation is :
(1/so) + (1/si) = 1/f
and f of both lens is found by ff = ((1/f1) + (1/f2) - (d/f1f2))-1
for the thin lens it is
si2 = ((1/f2) - (1/so2))-1
For the thick lens I found
h1 = -(f1f2)d/f2 = -20
h2 = -(f1f2)d/f1 = -20
so = d - (h1 = 80
and that ff = 40 from the above equation
so
i had (1/80) + (1/si) = 1/40
solved for si = 80
However for thin lens I found
So1 = 100cm
f1 = 20 cm
Si1 = ((1/f1) - (1/so1))-1 = 25
then so2 = d - si1 = 10 cm - 25 cm = -15 cm
finally si2 = ((1/f2)-(1/so2))-1 = 60
obviously 60 does not equally 80 and I have no idea what I did wrong. I think that what I got for so for the thick lens is wrong because when i switch it to 120 i get 60 . However my professor said that so was 80.
Homework Statement
Find the effective focal length of the two lens system. The focal length of the first lens is 20 cm and the second lens is -20 cm with the separation between the two lens being 10 cm. Locate the principal planes. Locate the image of an object that is 1 m in front of the first lens. Express the location relative to the location of the second lens.
f1is 20cm
f2is -20
and the distance between the two is 10 cm
the object is 1m(100 cm) in front of the first lens
Homework Equations
for thick lense the equation is :
(1/so) + (1/si) = 1/f
and f of both lens is found by ff = ((1/f1) + (1/f2) - (d/f1f2))-1
for the thin lens it is
si2 = ((1/f2) - (1/so2))-1
The Attempt at a Solution
For the thick lens I found
h1 = -(f1f2)d/f2 = -20
h2 = -(f1f2)d/f1 = -20
so = d - (h1 = 80
and that ff = 40 from the above equation
so
i had (1/80) + (1/si) = 1/40
solved for si = 80
However for thin lens I found
So1 = 100cm
f1 = 20 cm
Si1 = ((1/f1) - (1/so1))-1 = 25
then so2 = d - si1 = 10 cm - 25 cm = -15 cm
finally si2 = ((1/f2)-(1/so2))-1 = 60
obviously 60 does not equally 80 and I have no idea what I did wrong. I think that what I got for so for the thick lens is wrong because when i switch it to 120 i get 60 . However my professor said that so was 80.
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