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Perminant Magnets and Static electricity

  1. Apr 27, 2004 #1
    Hello all. I have a couple of questions concerning static electricity, magnets, and dissimilar materials. My first question is can a permanent magnet moved past a dissimilar material be used to give it a static charge as if the magnet were a dissimilar material of opposite charge? My second question is if I were to have two disks (made of opposite dissimilar materials to develop a charge), one above the other with a tiny gap in between them, and I spun the disks past eachother in opposite directions, would a static charge build up on the disks? If this effect would work, would the presence of a permanent magnet do anything to enhance or modify the effect? I have looked up many different articles about electrostatic generators, and even a electrostatic multiplier, but I have still not been able to come to a clear conclusion about static being produced without the two disks making contact with eachother in any way. Any help/comments greatly appreciated.

    Thanks,
    Jason O
     
  2. jcsd
  3. Apr 27, 2004 #2
    "My first question is can a permanent magnet moved past a dissimilar material be used to give it a static charge as if the magnet were a dissimilar material of opposite charge?"
    No. A magnetic field crossing a material can induce the materials electrons to move, thus inducing a current. However, "static" potential is different, requiring a net postive or negative electrical field potential(meaning...not moving)

    "My second question is if I were to have two disks (made of opposite dissimilar materials to develop a charge), one above the other with a tiny gap in between them, and I spun the disks past each other in opposite directions, would a static charge build up on the disks?"
    Yes.

    "If this effect would work, would the presence of a permanent magnet do anything to enhance or modify the effect?"
    Always. A magnetic field effects charge distribution, but not in the way you may be looking for.
     
  4. Apr 27, 2004 #3
    Ok, thank you for your explanation. So, if I were to just have the nonmoving disk sitting on top of the… lets say, north pole of the magnet, the material would have a net positive charge? I think I'm interpreting this wrong. :confused: But making the bad assumption that I'm saying the right thing here, could one have a positive charged plate and a negatively charged plate (stuck to their respective magnetic poles), and have static potential when connecting a spark gap or a wire or something between them? Or, should I say, would the dissimiler material develope a static potential just from sitting idle on the pole of the magnet?
     
  5. Apr 28, 2004 #4
    - A "net postive" charge requires the removal of electrons from the material to somewhere other than the material.
    - A stationary magnetic field does not "attract" electrons, because a magnetic field is not electrically postive(or negative)
    - So, an electrically neutral, non-moving disk of any sort placed on top a magnet will not experience a net electrical charge in the presence of a stationary magnetic field.
     
  6. Apr 29, 2004 #5
    Thank you for the explanation. I think I understand now. Ok, I have one last question. Could I use a material that has been pre-made to hold a positive or negative static charge and use that to charge a disk (moving or nonmoving). I know that materials like cling wrap have a charge naturally because of their makeup. (Please correct me if I am wrong too). Could two naturally charged materials be spun next to eachother to create a greater static charge? or even just put close to eachother but still? I'm trying to understand the interactions of materials of this nature.

    Thanks,
    Jason O
     
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