How to calculate magnetic pole strength?

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Discussion Overview

The discussion revolves around calculating the magnetic pole strength of magnets and understanding the force between them through dipole-dipole interaction equations. Participants explore the theoretical and empirical aspects of determining magnetic dipole strength, as well as the complexities involved in such calculations.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant notes the need for a dipole-dipole interaction equation that includes magnetic dipole strength (m), defined as m=pl, where p is magnetic pole strength and l is the length of the magnet.
  • Another participant asserts that magnetic pole strength is determined empirically.
  • Some participants express surprise that a theoretical solution for calculating magnetic pole strength has not been established, citing the absence of the dipole-dipole interaction equation before 1998.
  • One participant argues that while there is a theoretical approach to determining dipole strengths, practical calculation is hindered by numerous variables, including the geometry and material properties of the magnets, as well as their manufacturing processes.
  • It is mentioned that measuring magnetic pole strength directly is often more feasible than calculating it due to the complexities involved.
  • Another participant emphasizes that many real-world physics problems are too complicated for hand calculations, necessitating experimental or computational solutions.

Areas of Agreement / Disagreement

Participants generally agree that calculating magnetic pole strength is complex and often impractical, leading to a reliance on empirical measurement. However, there is no consensus on the feasibility of a theoretical solution, with differing views on the existence and applicability of such solutions.

Contextual Notes

Participants highlight limitations related to the dependence on specific material properties and geometrical factors at nanometer scales, which complicate the calculation of magnetic pole strength.

abdo799
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I have 2 magnets , i need to know the force between them , I searched a lot , conclusion was : we need to use a dipole-dipole interaction equation , which included m, which the magnetic dipole , i searched how to calculate it , and this is what i found . m=pl where p is magnetic pole strength and l is length of the magnet . I searched a lot on how to calculate p and found nothing.
 
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It's determined empirically.
 
Simon Bridge said:
It's determined empirically.
It's so weird that no one tried to solve this , even the equation of the dipole-dipole interaction didn't exist before 1998
 
Not really - we know, in principle, how to go about it ... it's just that there are too many variables for the solution to be practical.

The dipole strengths depend on all the magnetic domains inside the magnet - which depends on the geometry of the magnet, the material it is made out of, and how it was made. Do you know all those things about your magnets - at nanometer scales? Much easier just to measure it.

Note: the "effective dipole" approach is only an approximation.
 
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abdo799 said:
It's so weird that no one tried to solve this , even the equation of the dipole-dipole interaction didn't exist before 1998

You'll find that a lot of "real world" physics problems are just too complicated to be worth solving by hand. We have to solve them either by experiment or using a computer simulation.
 

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