Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What happen to a metal bar near a Van de Graaff?

  1. Feb 8, 2012 #1
    When I place a metal bar near a Van de Graaff, which generate hugh amount of positive charges on its surface, if I hold it for a period of time, will it be possible to magnetize this metal bar? what happen to its internal molecula structure?
    Does anyone have any suggestions?
    Thanks in advance for any suggestions
  2. jcsd
  3. Feb 8, 2012 #2


    User Avatar

    The metal bar has a finite (and VERY small) capacitance. The potential of the bar will match that of the Van de Graaff, and the charge density on the surface could be calculated based on the capacitance.

    The Van de Graaff can generate fairly high voltages, but not infinitely high - not high enough to cause a breakdown at a molecular level of a metal.
  4. Feb 8, 2012 #3
    What if I place Van de Graaff near the ground for a long period, will the ground have higher capacitance to be magnetized with this positive charges from the Van de Graaff?
    Do you have any suggestions?
    Thanks you very much for any suggestions
  5. Feb 8, 2012 #4
    I sounds like you are mixing up electric polarization with magnetization.

    What would happen is that when the bar is near the surface of the Van de Graaff generator, the positive charge of the generator would create an electrostatic field which would attract the electrons in the metal causing the side closest to it to become negatively charged compared to the other side (electric polarization). Magnetization happens when a magnetic field aligns the tiny magnetic dipoles of a material (magnetic polarization) and some of the dipoles stay aligned after the field is removed.

    Since Van de Graaff generators only generate electrostatic fields, they cannot magnetize an object, no matter how long it's held near it.
    Last edited: Feb 8, 2012
  6. Feb 8, 2012 #5
    The electrostatic force experienced by positive charges from Van de Graaff generators is the interaction between negative charges from the ground's surface. The electric field is the force per charge at a given location and is perpendicular to Van de Graaff generators' surface. Whenever there is an electric field, would it be true that there is also a magnetic field existed?

    If the magnitude of an electric field from Van de Graaff generators is strong enough to produce a spark to the ground, will it generate enough magnetic field to polarize a small local area on the ground's surface?
    Last edited: Feb 8, 2012
  7. Feb 8, 2012 #6
    Any suggestions?
  8. Feb 9, 2012 #7


    User Avatar
    Gold Member

    oem7110, I do have a suggestion: study and learn basic physics. You demonstrate a lack of understanding of the fundamentals.
    Above, you wanted to magnetize concrete using voltage. Then you wanted to magnetize water using voltage. Now, you want to magnetize a metal bar using voltage.

    In all three tries here in this forum you have been told by experienced scientists and engineers that you are talking "pseudoscience". That means, in case you can't handle words with more than ten letters, science fiction, or, pure bs.

    This is an opportunity for you to learn from this where your understanding is faulty.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook