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Homework Help: Microscopes and Vision

  1. Nov 30, 2016 #1
    1. The problem statement, all variables and given/known data
    - Why is it more useful to mark an objective lens [in a microscope] by its magnification rather than focal length?
    - Why might it be more convenient to think in terms of refractive power rather than focal length? [dealing with vision here]
    2. Relevant equations
    - thin lens equation: (1/f) = (1/s)+(1/s')
    - magnification (m) = (-s'/s)
    - Refractive power (R) = (1/f)
    - Total R of eye = R(cornea) + R(lens) = 40 D at far point, 43.5 D at near point.
    - Total R = R(eye) + R(corrective lens)
    3. The attempt at a solution
    - For the first question, I said that if you know m, then you could solve for the size of an object under a microscope pretty easily. Are there any other reasons that anyone could think of?
    - For the second, I honestly have no idea. To me, it seems just as reasonable to think about correcting vision in terms of the focal point of the eye/lens. I initially thought "well, glasses and contacts are in diopters, so it makes sense to think about correcting vision in this way," but couldn't we think of corrective lenses in terms of the focal point?
  2. jcsd
  3. Dec 6, 2016 #2
    Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.
  4. Dec 7, 2016 #3


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    Homework Helper

    The second one is pretty clear from the formulas you provided. You just add the powers if the lenses are close to each other!
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