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Medal Detectors' myth

  1. May 17, 2005 #1

    I always fascinated by the idea of Medal Detector, they are everywhere. In Libraries, stores... What is the myth behind those machines?
  2. jcsd
  3. May 18, 2005 #2


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    Hopefully you mean metal detector. The deal is that they send electromagnetic waves in the direction you point them, and tell you when the signal comes back.
    They work because metals reflect EM waves. Visible light is a type of EM wave, and we all know how metals are generally shiny.
  4. May 18, 2005 #3


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    Those are not metal detectors. The only place you'll find metal detectors are at airport security. They detect the signal from a tag inserted in the product.
  5. May 18, 2005 #4


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    Though if they are, I think I'll not visit the neighborhood where PrudensOptimus lives. :uhh:
  6. May 18, 2005 #5


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    In reality these devices are loosely tuned oscilators. When a piece of metal is inside the EM field the reactance of the tuning circuit is altered and the frequency changes. The changing frequency and not an echo is used to detect the presence of a metal.
  7. May 18, 2005 #6
    Here is a related question:

    I have about 2 ounces of surgical steel in my arm. Why can I pass through metal detectors without this being detected?

    Is it the type of metal?

    Is it that it is inside my arm?
  8. May 18, 2005 #7


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    It is probably the amount. I remember eharing that metal detcetors are callibrated to ignore metal in amounts too small to be a weapon. Only makes sense; can't have them going off every time somone with fillings in their teeth tries to walk through.

    My mom has a screw in her leg, and she sets off the metals detectors everytime she goes to the airport. But that's a lot more than two ounces.
  9. May 18, 2005 #8
    i went through a metal detector last year at NBC studios. it went off, and they made me go back. i started to take out my change and he said "no, that wouldn't set it off".

    turns out it was the foil from my gum wrappers!
  10. May 18, 2005 #9


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    The metal underwire in my bra set off the metal detector at the airport a couple of years ago, my daughter's small belt buckle set it off last time.
  11. May 18, 2005 #10
    It looks from this site:
    Metal Detectors
    Address:http://www.mwscientific.com/metal_det_test_sf.htm [Broken]
    like surgical pins aren't likely to set a detector off. Is your "2 ounces" the sum of the weight of several individual pins? If not, then you're just lucky.
    Last edited by a moderator: May 2, 2017
  12. May 18, 2005 #11
    No one has tackled the "myth" of metal detectors yet. The myth associated with metal detectors is that they can be set off if you have been abducted by space aliens and had an alien implant inserted into your body somewhere.
  13. May 18, 2005 #12
    Nice, zooby :tongue:

    I suppose he merely meant to ask "how do these machines work?"
    Or maybe he was looking for answer like yours. :uhh:
  14. May 18, 2005 #13
    He was clearly fishing for info about space aliens.
  15. May 18, 2005 #14
    The zipper in my pants set off the alarm at the airport. You just need to tell them that you have something in your arm, and ask for them to search you with the want, and you will be set.
  16. May 19, 2005 #15


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    I have to go through metal detectors frequently for professional reasons and really wish I could buy all non-metalic clothing (wooden belt buckles, zipper free clothes with non-metal buttons, etc.).
  17. May 19, 2005 #16


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    Get button up pants :D
  18. May 19, 2005 #17


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    If you think that I'm not going to pursue this in GD, you're nuts.

    If you're implying that to search Crosson is to want him, then I pity anyone in the security business. Elsewise, I will assume that you meant wand. :tongue:

    If you were a professional nudist, this wouldn't be a problem.

    Okay, I'm going back to GD where I belong...
  19. May 20, 2005 #18


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    I go through airports 8+ times per year, I've never been stopped.
  20. May 20, 2005 #19


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    Zipper in your pants... Right. You mean the foil-wrapped cuke.
  21. May 20, 2005 #20


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    Is there anyone that doesn't like that movie?
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