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Homework Help: Images from Two Parallel Mirrors problem

  1. Nov 20, 2007 #1
    The problem statement, all variables and given/known data

    Two parallel mirrors that face each other are placed along and perpendicular to the x-axis at x = +11.00 m and x = -11.00 m. Assume that a point source of light is placed on the axis at x = +2.70 m. In principle, there will be an infinite number of images generated. Consider the locations of the four images of the point source with the smallest absolute values of image distance i. Going from left to right (i.e from negative to positive), what is the x-coordinate of the left most image?

    2. What is the x-coordinate of the next image?

    3. What is the x-coordinate of the next image?

    4. What is the x-coordinate of the right most image?

    I really do not know where to start, so any help appreciated
  2. jcsd
  3. Nov 22, 2007 #2


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    Homework Helper

    Draw a sketch... first draw the reflections of the point source in the two mirrors... what are the coordinates of these two images. I'll call the I1 (reflection in mirror 1) and I2 (reflection in mirror 2). Now I1 and I2 also have reflections... I1 has a reflection in mirror 2... call it I12. you can get the coordinates of this image because you have the coordinates of I1, and therefore you know its distance from mirror 2... so I12 is located on the other side of mirror 2 at the same distance.

    And I2 has a reflection in mirror 1... call it I21. You can get I21's coordinates in a similar manner as you got I12's coordinates.

    that's 4 images... I1, I2, I12 and I21.
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