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Homework Help: Angular Magnification of Microscope

  1. Oct 10, 2008 #1
    The problem statement, all variables and given/known data

    Hey, I'm having trouble with this question on microscopes.

    A microscope is made up of an objective of power +100D and an eyepiece of power +50D, the two lenses being separated by 18cm. How far in front of the objective must an object be placed if the image of the object formed by the microscope is viewed by an emmetrope exercising 4D of accommodation? Assume the observer's eye is close to the eyepiece. What will be the angular magnification in this case?

    I worked out the object distance to be -1.07cm but I can't figure out how to get the angular magnification (the answer is 204.6x).

    Relevant equations

    Gauss Law

    The attempt at a solution

    I drew a diagram with the two lenses and labelled the distance between them (18mm). Then I worked backwards by treating the final image distance as 1/-8 as the person has to accommodate by 8D and from there I found the object distance for lens 2 which is the image distance for lens 1. Then I found the initial object distance. So now I'm stuck on the angular magnification. Can someone please show me the working out?

    Thanks! :)
  2. jcsd
  3. Oct 10, 2008 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    I'm not sure what role the 4D accomodation plays, but couldn't you take a slightly off-axis ray passing through the center of the 100D lens, and calculate at what angle it exits the 50D lens?
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