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Electric or Magentic fields dangerous?

  1. Jan 9, 2008 #1
    Ok, I understand that electricity moving through a wire produces a magnetic field (and I believe an electric field).

    My question is, can a strong enough electric field be felt by a person? I have felt a static field on a ballon that feels sort of prickly. But I'm not sure about a dynamic electric field produced through induction.

    I've also never felt a magnetic field.

    Could it be that electric and magnetic fields aren't able to be physically felt by our bodies?
     
  2. jcsd
  3. Jan 9, 2008 #2

    dst

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    You cannot feel a magnetic field much if at all but electric fields are very feel-able and very strange. Not sure about dynamic fields but I imagine they will be similar.
     
  4. Jan 9, 2008 #3

    berkeman

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  5. Jan 9, 2008 #4
    I did hear once that a very strong magnetic field could rip out the iron from your blood. I guess if one were really powerful, it could split apart the molecules in your body.

    I was wondering also, because in the Sun, it's matter is very affected by magnetic fields. I guess plasma has this property because it's charged.


    Well when I think of a laser, it's a combination of electric and magnetic field. So these together can cause burning and such.

    I actually am not concerned with the health affects. I just am curious to know what a magnetic field feels like.


     
    Last edited: Jan 9, 2008
  6. Jan 9, 2008 #5

    berkeman

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    If you could feel magnetic fields, then an MRI scan would not be much fun.
     
  7. Jan 9, 2008 #6
    You feel whatever your nerves react to,which is 99.99999999% force.Since you arent a ferromagnetic material you need a STRONG magnetic field to have a noticeable force on you.So thats why you dont feel it.

    Also a magnetic field can create currents and charge accumilation,but on a dielectric substance as a human its unoticeable.
     
  8. Jan 9, 2008 #7

    olgranpappy

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    Stand infront of the x-ray beam at your local accelerator. You will feel quite a lot of pain as your flesh melts.

    For a gentler electromagnetic sensation, you can just sit outside on a sunny day. It's called "tanning".
     
  9. Jan 9, 2008 #8
    I have just had MRI scanned and before taking the scan, the physician insisted asking me if I had an operation in the past. I was not so sure why.
    Being in an MRI is just normal except for some very loud noises like hammering around.
     
  10. Jan 9, 2008 #9

    berkeman

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    They asked because ferrous metal (steel screws, plates, etc.) would be a problem with the high magnetic fields used in the scan.
     
  11. Jan 9, 2008 #10

    f95toli

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    Also, even moderate magnetic fields ARE dangerous is you are wearing a pacemaker (which is why there are warning signs just about everywhere is labs with strong fields).

    But this is -as far as I understand- simply due to the fact that pacemakers are designed so that they can be controlled by an external magnetic field; i.e. stepping into a strong magnetic field might quite litteraly trigger the "off button" on the pacemaker. Also, high frequency magnetic pulses might presumably affect the timing.
     
  12. Jan 9, 2008 #11

    NoTime

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    Very strong magnetic fields, properly applied, can levitate living objects.
    There was one experiment done with a frog.
    I would imagine that would be an odd sensation. :smile:
    AFAIK the frog was not injured by the experiment.
     
  13. Jan 9, 2008 #12

    berkeman

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    No kidding? Did they make the frog eat something weird first?
     
  14. Jan 9, 2008 #13

    Claude Bile

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  15. Jan 9, 2008 #14
    Not feeling it does not mean it does not exist.

    While we, or our nervous systems may note the magnetic fields, I cannot find a reputable article that shows a human interaction with them. Insects, birds, and perhaps other migratory creatures use magentism and solar position to find thier place and vector thier migration path. People on the other hand don't move that far, that fast. Even migrating. We use things like...follow tree branch pointing at setting sun...kind of migration maps.

    I have no idea, and would enjoy seeing any links to research showing that humans actually use magnetosphere homing to some extent, but I (and this is pure speculation) suspect it will relate to a study on people with a better innate sense of direction.
     
  16. Jan 10, 2008 #15
    I did some work in a high field (6T) MRI and was able to "sense" the field. Other workers reported similar sensations. Disorientation was common, but did not result in ataxia outside the bore. Some of us noticed a sort of "fuzzy-headedness" where we took longer to do precision tasks. The effect typically took about 10 minutes to become noticeable and did not persist upon leaving the bore. Many of the workers also worked inside lower field units and did not notice the sensations there.
     
  17. Jan 10, 2008 #16

    dst

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    Considering it took 10T to levitate a frog, there must be a reasonably large force on whatever the hell it acts on even at 6T.
     
  18. Jan 10, 2008 #17
    I thought Tesla was an electric field measurement, and Gauss was a magnetic field measurement.

    How can Teslas measure a magnetic field?
     
  19. Jan 11, 2008 #18

    Cthugha

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    Gauss is the dimension of the magnetic flux density in CGS units.
    Tesla is the dimension of the magnetic flux density in SI units.

    1 Tesla is equivalent to 10000 Gauss.
     
  20. Jan 11, 2008 #19
    BTW, we didn't have a frog but did have to check the old myth about dollar bills being attracted due to the iron in the ink. They aren't. Although an aluminum ruler will flutter almost still in mid-air for a good thirty seconds.
     
  21. Jan 11, 2008 #20

    NoTime

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    No. My understanding is that water is slightly diamagnetic.
     
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