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Can Interferance cause magnification?

  1. Jul 11, 2004 #1
    There is this house down the street which has one of those new, white plastic vinyl fences around the front yard.
    This particular fence is constructed in such a way as the vertical members are the width of the spacing between members(about 2 inches or so)
    More importantly, the top of the fence line changes horozontaly, kind of like a wave(I suppose for aesthetic reasons) with some ornamental du-dad fashioned atop each vertical fence element.

    Anyway, when I drive to work each morning, the sun is above and behind the fence.
    I notice the interferance pattern, but a startling thing happens as I approach, roughly, about 100 feet from it:
    A black and white interferance image of the back fence, with all the du-dads, appears with exceptional crispness and is about 4-times larger(width-wise) than the fence itself.
    It is an awesome sight, an have seen it hundreds of times. It appears as though I am looking at a magnified negative image of the back fence with exquisite detail. When the sun is not behind it the image is barely noticable.
    Is this a common feature of interferance patterns?
    Also, if I take the time to take pictures, will the phenomenon show up?
  2. jcsd
  3. Jul 11, 2004 #2
    I should point-out that the exceptionally fine detail I see is with respect to the outline of the back fence and top du-dads. No "non-edge" detail is observable.
  4. Jul 11, 2004 #3


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    Well, if your eye can see it, so can a camera...

    - Warren
  5. Jul 13, 2004 #4
    Do you mean magnification of the fringes (by your first topic)?
  6. Jul 14, 2004 #5
    Where does the pattern appear? That's the only thing i can't follow. Sounds interesting though. Can you snap a few pictures?
  7. Jul 14, 2004 #6


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    I'm thinking what sporff is too [unless I misunderstood your message].

    In my Serway, it says that interference patterns only occur when the spacing between the slits is approximately that of the wavelength of the EMR.
  8. Jul 15, 2004 #7
    Thanks all, I've been away. I will more closely examine this to correct or further address the issue.
    I am not sure that this is not some type of optical illusion or mis-interpretation on my part. Nonetheless I will endeavor to more accurately experience the event(it has previously always been by a moving car), so I will do a "walk-by" in the next week.
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