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Homework Help: Eye focusing

  1. Nov 13, 2008 #1
    1. The problem statement, all variables and given/known data
    Suppose the lens in a human eye has far focal length equal to f0 = 40.1 mm, for distant objects to be in focus.
    A. An object K is 1.69 m from the lens. How much should the focal length change to focus on the object K?

    B.What is the magnification ( = image size divided by object size) for the object K?

    2. Relevant equations

    3. The attempt at a solution
    A. 1/1690+1/x=1/40.1
    x=41.0746 mm
    Thus, delta f = .9746 mm but that's wrong for some reason... but it's been a long week...

    B. -f2/f1=M

    Can someone help me out here?
  2. jcsd
  3. Nov 13, 2008 #2


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    Science Advisor
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    Hi haxxorboi! :smile:

    Shouldn't the 1/x be on the other side? :redface:
  4. Nov 13, 2008 #3
    *sigh* Yep, that'd be the issue... need either more sleep or more caffeine I guess...

    Problem solved.

    Thank you very much... I'm gonna go take a nap...
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