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Homework Help: How do I find the height of the image?

  1. Mar 24, 2009 #1
    1. The problem statement, all variables and given/known data
    A 1.80-cm-high object is situated 19.7 cm in front of a concave mirror that has a radius of curvature of 12.2 cm. Calculate (a) the location and (b) the height of the image.

    2. Relevant equations
    1/image distance + 1/object distance = 1/f

    3. The attempt at a solution
    f=1/2(12.2) = 11.1
    1/image distance + 1/19.7 = 1/6.1
    image distance = 8.836 cm

    then I thought to find the image height I'd just take 8.836 cm - 1.8 cm = 7.036 cm but this is incorrect.
  2. jcsd
  3. Mar 24, 2009 #2


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    Science Advisor
    Gold Member

    The ratio of image height to object height = the magnification will equal the ratio of distance from image over distance of the object to the mirror or lens.
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