Is the Homopolar Motor a Reactionless Drive?

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Discussion Overview

The discussion revolves around the concept of the homopolar motor and whether it can be classified as a reactionless drive. Participants explore the implications of electric currents and magnetic fields in relation to Newton's third law of motion, particularly in the context of momentum conservation.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant asserts that passing an electric current through a conducting magnet at a right angle to the magnetic field results in a force that appears to violate Newton's third law, suggesting a reactionless drive.
  • Another participant counters that electromagnetic fields always conserve momentum, implying that the initial claim may not hold under scrutiny.
  • A participant expresses skepticism about the relevance of electromagnetic field momentum conservation to the homopolar motor scenario, questioning how momentum is conserved in practical terms and suggesting that the magnetic field's momentum may not be significant for the concept of a reactionless drive.
  • One participant emphasizes that electric and magnetic fields are inherently part of electromagnetic fields, suggesting a broader context for the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are competing views regarding the implications of momentum conservation and the classification of the homopolar motor as a reactionless drive.

Contextual Notes

Participants express uncertainty about the role of the magnetic field's momentum and its practical implications for the concept of a reactionless drive. There are unresolved assumptions regarding the definitions and interactions of electric and magnetic fields in this context.

MS La Moreaux
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If an electric current is passed through a conducting magnet at a right angle to the magnetic field lines, the magnet should experience a force at right angles to both the flux and the current. This is a linear version of the homopolar motor. Since the magnetic field is not attached to the magnet, it would seem that there is no reaction to this force, thus violating Newton's third law of motion.

Mike
 
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Thanks for the references, but they seem only to apply to EM fields. The case I described involves only a steady magnetic field and an electric current. The current obviously requires an electric field, but I am not inclined to believe that it is relevant in this case. I realize that it is unlikely that laws would be violated, but I do not see how the conservation of momentum is achieved in this situation. Even if the total momentum is conserved by considering the momentum of the magnetic field, if any, it would not seem to prevent the apparatus from being a reactionless drive for practical purposes, since I do not believe that any momentum of the magnetic field would be of concern for the purpose. The object of the reactionless drive is to move the apparatus through empty space.

Mike
 
Electric and magnetic fields are EM fields.

Thread closed.
 

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