Talk:Homopolar motor

message: I've changed my mind about the merge. No other elecrical motor and generator articles are merged on Wikipedia. Hopefully I've made it unnecessary by adding a brief description at the start. The existing material I've now put under the heading "Sources of Confusion" that I've seen used in other Wikipedia articles. I've also restored or rewritten some deleted material that I hope you agree now makes sense under this new heading.
D.keenan 02:03, 1 December 2006 (UTC)
thread_title:  Merge? 

message: Despite our well cited history section that says "The homopolar motor was the first electrical motor to be built. Its operation was demonstrated by Michael Faraday in 1821", IP editor 85.222.223.193 keeps inserting a claim that it was invented by Serbian electrical engineer Andrija Radović" in 2004. And, naturally, he is edit warring to push this POV. --Guy Macon (talk) 15:47, 12 August 2012 (UTC)
replies: text: You are obviously right to remove the absurd claim that the homopolar motor was invented by Andrija Radović in 2004.  There's absolutely nothing new (or particularly useful) about the homopolar electric motor.  It's basically a pedagogical curiosity.  - Eb.hoop (talk) 16:49, 12 August 2012 (UTC)
replies: text:  Now now... It is also a great converter of live batteries to dead batteries! <smile> --Guy Macon (talk) 00:38, 13 August 2012 (UTC)
thread_title:  Invented in 1821 or 2004? 

message: For possible inclusion in this article:
Homopolar motor with winding having multiple turns: US Patent US5144179  1992-09-01 [ http://www.google.com/patents/US5144179 ] and EP0507726  1992-10-07 [ http://www.google.com/patents/EP0507726 ]
Superconducting homopolar motor: [ http://www.ga.com/superconducting-dc-homopolar-motor ]
--Guy Macon (talk) 03:23, 1 October 2012 (UTC)
thread_title:  Superconducting? Multiple turn?  

message: I disagree from what I've read on the homopolar motor that it is low current because it is only a one-turn loop.  While multiple loops would require multiple sliding contacts, and that would increase voltage, that is not the point.  The point is that it is a HOMOPOLAR generator/motor, in that there is no crossing of any magnetic field gradients, at all.  The loops spin within the same polarity, axially, and therefore this effect should not exist per common electrical theory.  No doubt they exist, and have been built in up to 1.5 megaAmpere versions at the University of Texas at Austin, used to power rail-gun experiments with extremely high current requirements.  There are also megawatt superconducting homopolar motors contracted of late by the navy.  However, it is HOMOPOLAR and a mystery to modern electrical engineering without abandoning traditional theory and adopting a fringe theory that is contended by someone somewhere.  —Regards, DonEMitchell (talk) 05:55, 3 January 2011 (UTC)
replies: text: There's nothing written in physics about magnetic field gradients and movement. The way this works is by lorentz force. There's a current running through a wire, with a constant magnetic field. The lorentz force will work perpendicular to the direction of the current and the direction of the magnetic field. The current goes "down", the magnetic field points outwards, so the lorentz force will be . Not really a mystery. Ragnagord (talk) 17:49, 12 January 2013 (UTC)

text: It's not a question of fringe theories. It's just that the lines-of-flux model commonly used by working electrical engineers is a simplification that works just fine on most kinds of motors but not on homopolar motors. The physicists use theories (Lorentz force law and Faraday's law of induction) that work with any electric / magnetic circuit but are a somewhat difficult to visualize, thus the commonly used but limited lines-of-flux model used by EEs which leads to wrong answers in this limited case. A well-educated EE knows this and doesn't use the lines-of-flux model in situations where it breaks down. All of this is explained quite well in our Faraday paradox article. --Guy Macon (talk) 18:44, 12 January 2013 (UTC)
thread_title:  Violates traditional electrical engineering theory? 

message: There's a wee bit of a problem here.
The discussion (and the Definition of the Lorentz Force) cheerfully talks about the force produced without ever discussing whenceforth the reaction to that force comes. Newton's third law has yet to be repealed.
The point is that there has to be the possibility of relative motion between the current carrying conductor and the magnetic field orthogonal to the current. It's the reaction between the current and the magnetic field that produces the force. With the various configurations of the "one-turn motor" (homopolar might be a bit of an exaggeration) it may not be very obvious exactly what is producing the reaction to the force, but it is there nonetheless.Trainforrest (talk) 07:50, 13 January 2014 (UTC)
thread_title:  Except that.... 

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thread_title:  External links modified 

message: It would be nice if the explanation shows an example of the direction it moves depending on current direction and magnetic polarity, as these facts are actually hard to find.  — Preceding unsigned comment added by 2001:8003:E40F:F700:4C6:81B2:7C37:561C (talk) 13:24, 14 November 2020 (UTC)
thread_title:  Polarities