Is there a magnetic field around a moving single charge?

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Discussion Overview

The discussion centers around whether a magnetic field exists around a moving single charge, specifically in the context of charged hydrogen ions (H+) moving through space without electrons. The conversation explores theoretical implications and interpretations of electromagnetic principles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if a magnetic field is produced by moving charged hydrogen ions (H+) in the absence of electrons, suggesting that magnetic fields arise from the relative motion of electrons and protons.
  • Another participant asserts that a magnetic field would indeed be present around an isolated moving charge.
  • A different viewpoint emphasizes that current, as defined in Maxwell's equations, can be constituted by protons or alpha particles, indicating that they can also generate magnetic fields.
  • One participant references Lorentz transformations to argue that a moving charge creates a magnetic field, cautioning against the assumption that this field represents an infinitesimal element of current due to charge conservation concerns.
  • Another participant reiterates the point about Lorentz transformations and the relationship between electric and magnetic fields, while also expressing a philosophical view on the unity of electricity and magnetism.

Areas of Agreement / Disagreement

Participants express differing views on the conditions under which a magnetic field is generated by a moving charge, with some agreeing that a magnetic field exists while others question the implications of charge conservation and the nature of the current.

Contextual Notes

The discussion includes assumptions about the nature of magnetic fields and the role of charge conservation, which remain unresolved. The implications of Lorentz transformations and the definition of current are also points of contention.

lenfromkits
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is there a magnetic field around a moving "single" charge?

Quote: "All moving charged particles produce magnetic fields."

Hypothetically - if you took a bunch of charged hydrogen ions (H+) and moved them through space, would there be a magnetic field around them? (ie, there are no electrons anywhere in this experiment, only protons)

From what I understand, a magnetic field only occurs when you have electrons amidst the positively charge protons such that - relatively speaking - in the case of a current, the electrons are moving one direction while the protons move the other.

Is there anywhere I can find information about this specific test?

Thanks!
:)
 
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Yes, there would be a magnetic field around an isolated moving charge.
 


Consider that current - an element of Maxwell's equations for electromagnetism - is measured as charge-per-unit-time, moving across an arbitrary boundary.

The nature of the current-bearing elements don't matter. Protons are fine, or alpha particles (helium nuclei +2) they make a dandy magnetic current as they dash off.
 


It certainly makes a magnetic field. An easy way to prove this is that under a Lorentz transformation, a pure electric field becomes a mixture of electric and magnetic fields.

What you have to watch out for is the assumption that this is "the" field of an infinitesimal element of current. Maxwell's equations imply charge conservation, but an isolated infinitesimal element of current violates charge conservation.
 


bcrowell said:
It certainly makes a magnetic field. An easy way to prove this is that under a Lorentz transformation, a pure electric field becomes a mixture of electric and magnetic fields.

What you have to watch out for is the assumption that this is "the" field of an infinitesimal element of current. Maxwell's equations imply charge conservation, but an isolated infinitesimal element of current violates charge conservation.

Oooh! Whenever someone thinks like me, it's a clear sign of brilliance, I figure.

There aren't many examples of discussing electrostatics, so I'd started a thread called Postulate: EVERY field has a "magnetic" equivalent. under General Relativity,
and you'll see my cleverness is only rivaled by my humility. And modesty.

Anyhow, I agree thoroughly that electricity and magnetism are a unity with apparent differences, due principally to our frames of reference.
 

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