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Homework Help: Why do Parallel Mirrors produce infinite mirrors?

  1. Oct 2, 2009 #1
    1. The problem statement, all variables and given/known data
    Hi, I've got this question that is asking why mirrors placed in parallel will produce an infinite number of images.

    2. Relevant equations

    3. The attempt at a solution
    What I think is that the image formed in the first mirror would reflect off the second mirror, forming a second image which would then reflect off the first mirror and so on.

    The problem here is that I have no idea if this is correct (I couldn't find anything in my textbox or on the Net) and also , if it is correct, I need a clearer way of explaining it.

    Thanks in advance!
    Last edited: Oct 2, 2009
  2. jcsd
  3. Oct 2, 2009 #2


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  4. Oct 2, 2009 #3
  5. Oct 2, 2009 #4


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    From where shall I start? Do you know the laws of reflection?

  6. Apr 23, 2010 #5
    Plane Mirrors placed facing each other (parallel) actually does not produce infinite images, It will though in infinite time.
    Say the guy with the phone in that picture leaned on one mirror while the other is placed just over a metre in front. His image(of his anterior aspect that is) will be formed after approximately 1/300,000,000 second. Image of his back will take a further 1/900,000,000 seconds more if he is one foot deep. Now in one second alone we have about 300,000,000 (300 million) images. After just half a minute you'll have enough images to keep you occupied for over 70 years if you can manage to count four images a second. Nothing said of the images behind you. Well, that seems like infinity to us.
  7. Apr 23, 2010 #6
    Like this:


    Note that image1 is the place where the biggest reflection will be seen. This is the reflection of the object in the left mirror. image2 is the reflection of image 1 in the right mirror. The next image is the reflection of image2 in the left mirror again, but it's to the left and doesn't fit in the picture. The images you see. will be getting farther away and smaller.

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