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I dont understand homopolar motors

  1. Dec 20, 2015 #1
    I understand the diagram above where the blue stuff might be mercury like in Faraday's mercury motor. I dont understand why the liquid moves but.... it is a conductor so why doesnt the current (moving electrons) feel the force and leave the liquid stationary?
    Similarly in this motor its the liquid that moves?

    Many Thanks
  2. jcsd
  3. Dec 20, 2015 #2

    David Lewis

    User Avatar
    Gold Member

    There are homopolar motors that exert a force on the electrons in the (solid) rotor, and the electrons then carry the atomic nuclei with them, for example in an electrostatic voltmeter.

    However in this case I believe the cell exerts an electrostatic force on the electrons in the copper wires and in the liquid, and the moving electrons create a magnetic field. What we are seeing is the interaction between the permanent field magnet and the magnetic field created by the current.
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