Does moving an insulating cylinder produce a magnetic field?

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Discussion Overview

The discussion revolves around whether moving an insulating cylinder produces a magnetic field, particularly focusing on the implications of charge movement in insulators and dielectrics. Participants explore the relationship between charge motion, current, and magnetic field generation, as well as historical perspectives on the topic.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Historical

Main Points Raised

  • Some participants propose that moving an insulating cylinder does not produce a magnetic field because the electrons are bound and cannot create a current.
  • Others argue that if there is charge in motion, this constitutes a current and thus a magnetic field is produced.
  • A participant questions the nature of the material described as "full of dielectric," seeking clarification on the context.
  • One participant mentions a specific scenario involving a sphere filled with a dielectric and its implications for charge movement and magnetic field generation.
  • Historical context is provided regarding the 19th-century debates on the electrodynamics of moving bodies, referencing investigations by Röntgen and Eichenwald that concluded moving polarized dielectrics do produce a magnetic field.
  • Another participant highlights the significance of Einstein's work on the electrodynamics of moving bodies as a pivotal moment in the development of modern physics.

Areas of Agreement / Disagreement

Participants express differing views on whether moving an insulating cylinder generates a magnetic field, with some asserting it does not due to the nature of insulators, while others maintain that any moving charge constitutes a current that produces a magnetic field. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There are unresolved questions regarding the definitions and conditions under which charge movement leads to current and magnetic field generation, particularly in the context of dielectrics and insulators.

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Suppose that we have an insulating cylinder with ##\rho_q##. If i move the cylinder towards ##+\hat{n}##, will it produce a magnetic field? My assumption is that since we have an insulator, then the electrons are bound and there cannot be a current, thus a magnetic field is not produced. Also, does this happen if we have a material full of dielectric?
 
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Assassinos said:
If i move the cylinder towards , will it produce a magnetic field? My assumption is that since we have an insulator, then the electrons are bound and there cannot be a current, thus a magnetic field is not produced.
If there is charge in motion then this is a current and there is a magnetic field.
Assassinos said:
Also, does this happen if we have a material full of dielectric?
I don't understand what you are asking here. What material is full of dielectric?
 
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Ibix said:
If there is charge in motion then this is a current and there is a magnetic field.

I don't understand what you are asking here. What material is full of dielectric?
Assume a sphere of radius R, and from 0 to R the sphere is filled with a dielectric of permittivity ε.
 
Is it charged and moving? If so, there's a current.
 
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Assassinos said:
My assumption is that since we have an insulator, then the electrons are bound and there cannot be a current
A moving charge density is a current: ##\vec j = \rho \vec v##
 
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One should add a comment to the question about the dielectric. That was a very hot question in the 19th century, where many physicists where very puzzled about the "electrodynamics of moving bodies", and it was indeed a question, what's the nature of polarization and if a moving polarized body would produce a magnetic field. This was investigated by Röntgen and Eichenwald, and confirmed that indeed a moving polarized dieelectric produces a magnetic field, which however only added on the puzzle about "electrodynamics of moving bodies".

The final solution of all these troubles was nothing less than Einstein's famous breakthrough paper in the Annalen der Physik titled modestly "On the electrodynamics of moving bodies" and lead to one of the "revolutions" in 20th-century physics, i.e., the (special) theory of relativity.
 
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