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Homework Help: Converging Lens

  1. Aug 9, 2006 #1
    How far away from a converging lens must an object be ( in terms of focal length, f ) so that the difference between the image distance and the focal lengh is 1% of the focal length?

    I tried to translate the words into an equation based on the thin lens equation but i dunno if it is right or how to solve it for x in terms of f: tell me if im right:

    1/xf + 1/(f+.01f) = 1/f

    please help! thanks.
     
  2. jcsd
  3. Aug 9, 2006 #2

    Chi Meson

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    "Difference" means subtraction.

    f-di=.01f so di=?

    then, find do.
     
  4. Aug 10, 2006 #3

    andrevdh

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    Seems right to me. You could also go the other way 0.99f.
     
  5. Aug 10, 2006 #4

    Chi Meson

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    Oops. di will be greater than f, so you were right there. di=1.01f .

    and do, call it "x" or "do" but not "xf"
     
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