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Permanent magnet motor working on repulsion force

  1. May 18, 2014 #1
    Sir what would be the life of permanent magnet motor which runs by the repulsion of north pols. Is magnets energy wasted during this repulsion process or not. Because it continuously work on repulsion of two north pols.
  2. jcsd
  3. May 18, 2014 #2


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    Gold Member

    Can you draw a diagram to show what's in your mind?
    Something like this?

    Attached Files:

    • hhhu.png
      File size:
      499 bytes
  4. May 18, 2014 #3

  5. May 18, 2014 #4
    Two (or more) North Poles will exert a repulsion on each other. This repulsive force can be converted into useful work. The amount of energy used to bring the two poles together will be MORE than the amount of work extracted from them. That is, you will be converting motion (generated externally) into heat. There is no such thing as a perpetual motion machine.
    The diagram you added shows NO moving parts. If I assume that the two disks are spinning on the shaft, then the bearing surface will wear, but the amount of wear per revolution obviously depends on the materials of construction. The two disks will quickly stop, converting most of the energy you used to start them spinning into heat (friction) but some into electromagnetic waves.
    To repeat the obvious, what ever energy you use to spin the disks will be only partially converted into movement of the shaft (if the shaft is also rotating). There is no such thing as a perpetual motion machine.
    Last edited: May 18, 2014
  6. May 18, 2014 #5


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    Staff: Mentor

    Welcome to the PF. We do not discuss perpetual motion machines (PMMs) or "free energy" here at the PF. That is in the Rules (see Site Info at the top of the page). Thread is locked.

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