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Lens image problem!

  1. Jul 1, 2009 #1
    An object 1.95 cm high is placed 11.2 cm in front of a convex mirror with a radius of curvature of 9.8 cm. Where is the image formed??

    So i know Di= (Doxf)/(Do+f).....(11.2 x 9.8)/ (11.2 + 9.8) = 5.23 cm

    However, the correct answer is 3.41 cm

    What am i doing wrong here? I know that the 9.8 may not be the focal length but how do i relate the height to the focal length??
  2. jcsd
  3. Jul 1, 2009 #2


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    Focal length of the convex mirror = R/2 = 9.8/2 = 4.9 cm.
  4. Jul 1, 2009 #3
    do i even need to use the height of the object??...if so how?
  5. Jul 1, 2009 #4
    nevermind i got it! thanks!!
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