What is magnetic pole? What is sink/source?

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    Magnetic Pole
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Discussion Overview

The discussion revolves around the definitions and concepts of 'magnetic pole' and 'sink/source', exploring their similarities and differences. Participants inquire about experiments and equations related to locating magnetic poles and the characteristics of magnetic fields, particularly in relation to single electrons and monopoles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants differentiate between monopoles and dipoles, stating that monopoles act as sinks/sources with nonzero divergence, while dipoles do not, leading to the conclusion that they are not the same.
  • There is a suggestion that using a Hall probe could help locate magnetic poles, but some participants express skepticism about the meaningfulness of identifying magnetic poles in the same way as electric dipoles.
  • Experiments have been conducted to search for magnetic monopoles, including using particle detectors and extracting monopoles from meteor dust, but no monopoles have been found.
  • Participants question the definitions of "field pole" and "sink/source," and how these relate to the attraction of opposite magnetic fields.
  • There is a discussion about the superposition of magnetic fields, particularly regarding the magnetic dipole moment of a single electron and how magnetic fields behave differently from electric fields.
  • One participant notes that without magnetic charges, magnetic field lines form closed loops, suggesting that the term "pole" is merely a convenience for orientation rather than an indication of actual magnetic charges.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of magnetic poles and sinks/sources, with no consensus reached on these concepts. The discussion remains unresolved regarding the nature of magnetic poles and their experimental detection.

Contextual Notes

Participants highlight limitations in definitions and the assumptions underlying the concepts of magnetic poles and sources/sinks. There are unresolved questions about the behavior of magnetic field lines and the implications of monopole existence.

marion.s
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What is the definition of 'magnetic pole' and 'sink/source'? Same thing?

Are there any experiments and equations that can locate magnetic poles?

How far away are magnetic north and south poles of single spinning electron?
 
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There are monopoles and there are dipoles. Monopoles are sinks/sources (e.g. point masses, charges) which give a nonzero divergence. Magnetic dipoles (the type you find in solenoids, say) give zero divergence because on the whole they are neither sources nor sinks. So no, they are not the same thing.

Um, I suppose you could wave a Hall probe around in space. I don't think it's very meaningful to point to something and call it a magnetic pole in the same sense as you could with one half of an electric dipole, precisely because there are no sources/sinks. I guess this probably renders the electron thing moot too.
 
Some people have built particle detectors to search for magnetic monopole "rays", pull monopoles out of meteor dust (and moon dust?), and even built the magnetic equivalent of a toroidal electric circulating current, using ground-up meteor dust in balls of epoxy. No monopoles found.
Bob S
 
Last edited:
darthoctopus said:
There are monopoles and there are dipoles. Monopoles are sinks/sources (e.g. point masses, charges) which give a nonzero divergence. Magnetic dipoles (the type you find in solenoids, say) give zero divergence because on the whole they are neither sources nor sinks. So no, they are not the same thing.

F= k* q1*q1/r^2

F= k* m1*m2/r^2

These equations describe both poles and sources/sinks of electric and gravity fields to be in the same location, so why is that not the definition of what poles and source/sinks are - the points of attraction/repulsion?

How do you define "field pole"? How do you define "sink/souce?


Um, I suppose you could wave a Hall probe around in space. I don't think it's very meaningful to point to something and call it a magnetic pole in the same sense as you could with one half of an electric dipole, precisely because there are no sources/sinks. I guess this probably renders the electron thing moot too.

How do you call the place in a magnetic field towards which opposite magnetic field gets attracted to? Why is that not a sink?
 
Bob S said:
Some people have built particle detectors to search for magnetic monopole "rays", pull monopoles out of meteor dust (and moon dust?), and even built the magnetic equivalent of a toroidal electric circulating current, using ground-up meteor dust in balls of epoxy. No monopoles found.
Bob S

How do you define "pole"? How do you define "sink/source"?

How far away are magnetic north and south of a single electron?

Do magnetic field lines actually go through poles or circle around them?
 
Superposition of magnetic fields

Looking at a single electron as a source of magnetic dipole moment we may notice that even though these two magnetic poles have to be extremely close to each other the magnetic fields do not cancel out as electric fields would. What are the principles, definitions and equations describing superposition of magnetic fields?
 
without magnetic charges, magnetic field lines form closed loops. The term "pole" is just a convenience of orientation of the magnetic field with respect to a coordinate system. It doesn't mean there are actually poles, as in charges. "dipole moment" contains the same type of information: orientation of magnetic field in coordinate system.
 

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