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How to find the magnification

  1. Mar 28, 2007 #1
    1. The problem statement, all variables and given/known data
    [​IMG]


    2. Relevant equations
    I am unsure of how to find the magnification:
    i know the formula is I/O


    3. The attempt at a solution
     
  2. jcsd
  3. Mar 28, 2007 #2
    google "magnification equation" that should help you
     
  4. Mar 29, 2007 #3
    1 / f = 1 / do + 1 / di where f = 13.8 cm and do = 27.6 cm
    i get: 27.6, but the computer tells me that it is incorrect...
     
    Last edited: Mar 29, 2007
  5. Mar 29, 2007 #4
    Does anyone know what am doing wrong?
     
  6. Mar 29, 2007 #5

    hage567

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    This is not correct for finding the magnification.
    You were correct when you said M=image height/object height. Magnification can also be expressed in terms of the object distance and image distance (you get this by geometry). So M=-q/p, where q is the image distance and p is the object distance. See if that helps.
     
  7. Mar 29, 2007 #6
    so the image distance is 27.6 and the object distance is 27.6 as well, so would it be 27.6/27.6
     
  8. Mar 29, 2007 #7

    hage567

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    Watch out for your signs. The equation has a negative sign in front of it. So if both p and q are positive, your magnification will be negative. Do you know what that means?
     
  9. Mar 29, 2007 #8
    so the answer would be -1
     
    Last edited: Mar 29, 2007
  10. Mar 29, 2007 #9
    Would that be correct?
     
  11. Mar 29, 2007 #10

    hage567

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    That would be my answer.
     
  12. Mar 29, 2007 #11
    thank you!
     
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