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Homework Help: Angular Magnification for a Microscope

  1. Oct 3, 2014 #1
    1. The problem statement, all variables and given/known data
    The eyepiece of a compound microscope has a focal length of 2.50 cm and the objective has a focal length of 1.8 cm. The two lenses are separated by 22 cm. The microscope is used by a person with normal eyes (near point at 25 cm). What is the angular magnification of the microscope?

    2. Relevant equations
    M = (25)(s'1)/( (f1)(f2) )

    3. The attempt at a solution
    So I understand that the 25 comes from the near point of the eye for a human. However, with f1 defined as the focal length for the objective lens (1.8 cm) and f2 defined as the focal point for the eyepiece (2.50 cm), I don't know how to calculate the location of the image since I don't know the location of the object. Can anyone clarify this for me? Thank you in advance.
  2. jcsd
  3. Oct 4, 2014 #2


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    From what I've found online, the idea is to have the image from the eyepiece form at infinity to minimize eyestrain. From this information, you should be able to deduce where the object must be for the eyepiece. The object distance for the objective is adjusted so that its image forms at the right location to meet the criterion above.
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