A moving magnet in a linear electric field

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Discussion Overview

The discussion centers on the behavior of a moving magnet within an electric field, exploring theoretical implications, experimental possibilities, and the relationship between magnetic and electric forces. Participants examine the potential for groundbreaking experiments and the complexities of existing theoretical frameworks, including the Heaviside equations and relativistic electrodynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that a moving magnet in an electric field might produce effects similar to those of a charged mass in a magnetic field, but notes a lack of literature on the topic.
  • Another participant raises concerns about the Heaviside equations, stating they associate electric charge with mass but not magnetic charge, complicating the understanding of magnetic mass experiencing force.
  • Several links to academic papers are shared, indicating that the topic is complex and debated, with one participant expressing uncertainty about making definitive statements.
  • One participant proposes a simple experimental setup involving dropping a bar magnet between capacitor plates, suggesting that interpretation of results can be discussed later.
  • Another participant claims that existing papers contradict each other and argues that a moving magnet would require an inhomogeneous magnetic field to feel a force, while also disputing claims about moving magnets acquiring electric dipole moments.
  • A counterpoint is raised, asserting that a moving permanent magnet does indeed acquire an electric dipole moment from the perspective of an inertial frame, referencing the relationship between electric and magnetic polarizations in relativistic electrodynamics.
  • Concerns are expressed regarding the lack of proof for certain claims about the relationship between electric and magnetic polarizations in permanent magnets.
  • One participant acknowledges the standard nature of the relativistic electrodynamics argument presented.
  • Another participant expresses surprise at the assertion being considered proof.

Areas of Agreement / Disagreement

Participants express a range of views, with some supporting the idea that a moving magnet acquires an electric dipole moment, while others contest this claim. The discussion remains unresolved with multiple competing perspectives on the implications of moving magnets in electric fields.

Contextual Notes

Participants highlight the complexity of the topic, noting that existing literature presents conflicting interpretations and that assumptions about magnetic charge and force are not universally accepted.

GregM
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If a electrically charged mass travels thru a magnetic(m) field, it will accelerate at right angles to its velocity and the m-field. Under some conditions like this the charged mass will travel in a circular loop due to this magnetic force acceleration. This info is all over the internet. e.g.
https://courses.lumenlearning.com/b...on-of-a-charged-particle-in-a-magnetic-field/

What about a moving magnet in an electric field? A similar effect? Seems not a word has ever been written about it. Google returns nothing. Perhaps no-one has ever thought to do this experiment. Potential for a ground breaking 19th century style experiment here. Which one of us will be the neo Faraday? I wonder what the Heaviside equations predict.
 
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problem with the heaviside equations is they associate electric charge with mass, but not magnetic charge. Its harder to see how magnetic mass experiences force.
 
can't they just report the results of dropping a bar magnet between 2 large long capacitor plates? Debate about interpretation of the results should come later.
 
https://link.springer.com/article/10.1140/epjp/i2014-14215-y
https://iopscience.iop.org/article/10.1088/0143-0807/32/4/003/meta
https://iopscience.iop.org/article/10.1088/0143-0807/33/1/L02
https://iopscience.iop.org/article/10.1088/0143-0807/33/1/L03/meta

Those papers contradict each other because they're all wrong. A magnetic would require an inhomogeneous magnetic field to feel a force. There are some papers claiming that a moving magnet acquires an electric dipole moment, but they are also wrong.
 
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But the latter is correct. If you have a permanent magnet and view it from an inertial frame, where it's moving there's also an elecctric dipole moment. It's because the electric and magnetic polarizations of a medium are components of an antisymmetric 2nd-rank Minkowski tensor in a similar way as the electric and the magnetic field are components of such an antisymmetric tensor. The only difference is that due to the historical misconception of magnetization there's a sign change. So you have
$$F^{0j}=-F^{j0}=-E^j, \quad F^{jk}=-\epsilon^{jkl} B^l$$
and
$$P^{0j}=-P^{j0}=p^j, \quad P^{jk}=+\epsilon^{jkl} m^l,$$
where ##\vec{E}## are the electric, ##\vec{B}## the magnetic field components and ##\vec{p}## the electric and ##\vec{m}## the magnetic polarization of the matter.

Thus an uncharged permanent magnet which has only a magnetization in its rest frame has both an electric polarization and a magnetization in any other inertial frame.
 
"the electric and magnetic polarizations of a medium are components of an antisymmetric 2nd-rank Minkowski tensor"
There's no proof of that for a permanent magnet.
 
That's standard relativistic electrodynamics.
 
I didn't realize that was the proof.
 

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