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Homework Help: Perpendicular Mirrors Question

  1. Sep 19, 2008 #1
    perpmirrors.jpg perpmirrorsray.jpg

    1. The problem statement, all variables and given/known data
    In the figure are two perpendicular mirrors. The origin is shown by the axes. I am asked to find the positions of each of the images that the observer at point O sees.

    The coordinates that I found were (-1,2) , (1,-2) , and (1,2),
    however, my book insists that the answers are (-1,1), (1,-2), and (1,2)

    What am I doing wrong? I am a little bit unsure as far as drawing my rays for the image formed when light reflects off both mirrors. Do the lines extended behind the mirror surface have to meet?

    2. Relevant equations

    3. The attempt at a solution
    Last edited: Sep 19, 2008
  2. jcsd
  3. Sep 19, 2008 #2
    any thoughts would be appreciated?
  4. Sep 20, 2008 #3
    It seems to me that the image has to be an equal length on the other side of the mirror as the object is from the surface. So the image behind the top mirror would be 2 m behind and 1 m to the left of the origin. Thus (-1,2). Why doesn't my book have this as one of the answers? And I don't know where they got (-1,1). Am I misunderstanding something?
  5. Sep 21, 2008 #4
    nevermind, the book is wrong
  6. Nov 3, 2009 #5
    3 adjacent perpendicular mirrors Question.

    if three mutually _l_ mirrors r placed adjacent to each other then for a person standing in front of them number of images formed = 7.

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