Mathematical model for interaction force between magnetic fields?

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Discussion Overview

The discussion revolves around the search for a mathematical model that describes the interaction force between sources of magnetic fields, particularly in the context of ferromagnetic materials and permanent magnets. Participants explore analogies to electrostatic forces and the limitations of existing models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about a mathematical model for the force between magnetic field sources, similar to Coulomb's law for electric charges.
  • Another participant references the Lorentz force law, which describes the force on a charge moving in a magnetic field, but notes it may not directly apply to static magnetic sources.
  • A third participant discusses the concept of magnetic monopoles, stating that they have not been discovered and that magnetic poles always exist in pairs, leading to the idea of treating magnets as magnetic dipoles.
  • One participant expresses a specific interest in the forces between ferromagnetic materials, which do not involve moving electric charges, and seeks additional literature on the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific mathematical model for the interaction force between magnetic fields. There are multiple competing views regarding the applicability of existing laws and the nature of magnetic poles.

Contextual Notes

Participants note the limitations of existing models, such as the absence of magnetic monopoles and the need to consider magnetic dipoles instead. There is also an acknowledgment of the complexity involved in describing forces between ferromagnetic materials.

Psinter
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I wanted to know if there is a mathematical model to know the force with which a source of a magnetic field attracts or repels another source of magnetic field.

For example, the mathematical model for the electrostatic force a charged particle exerts over another charged particle is: F = k(\frac{Q_1Q_2}{r^2})

where:
k is a constant with value 8987551788\frac{Nm^2}{C^2}
Q_1 is the charge of particle 1 in Columbus
Q_2 is the charge of particle 2 in Columbus
r is the distance in meters between the center of each particleSo, is there a digested equation like that one but for magnetic fields?
 
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Psinter said:
I wanted to know if there is a mathematical model to know the force with which a source of a magnetic field attracts or repels another source of magnetic field.

Not sure exactly what you mean, but there is an analgous force law for magnetism. For a charge Q, moving with velocity v and magnetic field B, the Lorentz force law is \textbf{F}=Q(\textbf{v} {\times} \textbf{B}). Thus in the presence of both electric and magnetic fields, the net force on some charge Q would be \textbf{F}=Q(\textbf{E}+\textbf{v} {\times} \textbf{B}).
 
The analogue to an electric charge is a magnetic monopole. The fact is that the magnetic monopole does not exist (at least it hasn't been discovered so far). You will never be able to get an isolated 'North' pole or an isolated 'South' pole. Even if you break a magnet into two each half will form its own north and south poles. In other words the magnetic poles exist in pairs, an isolated magnetic pole does not exist. Nevertheless, it is still possible to approximately describe the force between two magnetic poles by a law of a similar form as Coulomb's law. It would be more accurate though to treat a magnet as a magnetic dipole; this is analogous to an electric dipole which consists of a positive and a negative charge separated by a small distance.
 
tannerbk said:
Not sure exactly what you mean, but there is an analgous force law for magnetism. For a charge Q, moving with velocity v and magnetic field B, the Lorentz force law is \textbf{F}=Q(\textbf{v} {\times} \textbf{B}). Thus in the presence of both electric and magnetic fields, the net force on some charge Q would be \textbf{F}=Q(\textbf{E}+\textbf{v} {\times} \textbf{B}).

You replied and me just finishing of looking at that equation in the book. Hehe.

I'm still looking for something. What I mean is specifically for ferromagnetic materials like permanent magnets which do not posses moving electric charges.

I found this in Wikipedia: here and here

Can someone recommend some more literature on those subjects?

physwizard said:
The analogue to an electric charge is a magnetic monopole. The fact is that the magnetic monopole does not exist (at least it hasn't been discovered so far). You will never be able to get an isolated 'North' pole or an isolated 'South' pole. Even if you break a magnet into two each half will form its own north and south poles. In other words the magnetic poles exist in pairs, an isolated magnetic pole does not exist. Nevertheless, it is still possible to approximately describe the force between two magnetic poles by a law of a similar form as Coulomb's law. It would be more accurate though to treat a magnet as a magnetic dipole; this is analogous to an electric dipole which consists of a positive and a negative charge separated by a small distance.
Yup just got that. Thanks.
 

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