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Homework Help: Help Needed Please!

  1. Sep 14, 2004 #1
    Hey all,
    Grade 11 physics assignment due tmrw and im having some trouble. Any help would be appreciated. So here it is:

    A candle of height 4.8 cm is placed 38.6 cm in front of a converging mirror with curvature 30.2 cm. What is the height of the image?

    Heres what I have:

    1/f = 1/Di + 1/ Do so..... 1/15.1 = 1/Di + 1/38.6 so Di=2.56


    Hi/Ho = -Di/Do so............ Hi/4.8 = -2.56/38.6 so Hi=-.32

    Ho= Height of object (candle)
    Do= Distance of object
    Di= Distance of image
    Hi= Height of image
    f=focus (which i have calculated to be 15.1)

    The answer i get is -.32cm which doesn't seem right to me. Am i doing something wrong? Missing something??

    As well.... a totally unrelated question- When looking at interference patterns of water through 2 openings, if the second nodal line is formed at an angle of 50 degrees, will n=1 or n=1/2?

    Thanks for any help!!!
    Last edited: Sep 14, 2004
  2. jcsd
  3. Sep 15, 2004 #2
    Are you unsure of the sign or the magnitude of your answer? Or both?
  4. Sep 15, 2004 #3


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    Science Advisor
    Gold Member

    Try solving the image problem backwards.
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