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How does electromagnetic interference work?

  1. Oct 7, 2012 #1
    I have to do a presentation on why cellphones are banned in hospitals, and i'm going to have to explain how electromagnetic interference from the waves a cellphone gives off can mess with medical equipment.

    Can someone please explain the physics behind this?
     
  2. jcsd
  3. Oct 7, 2012 #2

    phinds

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    Have you done ANY research on your own or do you just want to be spoon-fed the answer?
     
  4. Oct 7, 2012 #3

    davenn

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    dont get so worked up, its not going to encourage anyone to help you

    you obviously didnt look too hard in your 2 hours....
    in 10 seconds I got 1000's of hits in google....eg...

    http://en.wikipedia.org/wiki/Electromagnetic_interference

    http://www.jmkfilters.com/faq.htm

    http://www.infosecisland.com/blogview/18418-Medical-Devices-and-Electromagnetic-Interference.html

    cheers
    Dave

    PS wonder where you are from ? I have been into hospital for various lengths of stays, 7 times this year, culminating in open heart surgery a bit over a month ago.
    Hospitals here in Australia dont seem to have any problem with us patients or our visitors using cellphones, laptops, wifi, I-pads etc
     
    Last edited: Oct 7, 2012
  5. Oct 7, 2012 #4

    phinds

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    Well, my psychic powers are a bit off today so I stupidly did not realize that you had done 2 hours of searching for something that should take a minute or two.
     
  6. Oct 7, 2012 #5
    I've seen those websites but I'm looking for a more specific answer than any of those links provided. Like i said, i wanted to know exactly how this interference occurs and all the physics behind it, not just the fact that electromagnetic waves from cellphones make devices malfunction
     
  7. Oct 7, 2012 #6
    I'm from Canada, and it really isnt a big deal apparently people still use their phones and most websites say that this only happens when phones are within like 3cm of the machines, but i was asked to explain why phones are banned from hospitals soo idk thats what i gotta do i guess lol
     
  8. Oct 8, 2012 #7

    davenn

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    well it is as many of those www sites say, The RF is simply inducted into the circuits.
    Those induced RF voltages/currents then mix with the existing signals and cause instabilities in the circuits. In other cases if the RF signals are strong enough they can physically damage the inputs to sensitive IC's etc, that tho would be much rarer case as could happen in close proximity to high power broadcast transmitters

    when it boils down to it with the very low power levels from mobile phones, the chances of problems occurring lie somewhere between zero and nil ;)

    Anyway, thats the quick answer... for anything more, since its YOUR study, YOU need to do the research :)


    have fun studying

    Dave
     
  9. Oct 8, 2012 #8

    sophiecentaur

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    If you want detailed knowledge of a subject like RFI then you will need to spend more than two hours at it. Perhaps you need to learn effective searching techniques on the www and then you would have more time to read the technical stuff about the topic. Lesson number one will be that you will never find a link entitled "The exact answer to Ruzic's question". You have to be prepared to do a bit of synthesis with the information that you do manage to find. The Internet has made people very lazy in this respect, I'm afraid. It's turned them into Cabinet Ministers who demand a personal advisor for everything.
    Of course, you can always pay for a consultant to do the leg work for you.
     
  10. Oct 8, 2012 #9

    berkeman

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    I will give you an additional search term that you may not know about. Do a search for EMI information, and add the keyword rectification. Rectification from EMI RF radiation can cause at best DC errors in analog instrumentation, and at worst, fires from blown up power supplies. Use the search to help you understand how each problem can occur.
     
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