Calculating Magnetic Field Strength for a Simple Bar Magnet

  • Context: Undergrad 
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    Magnetism
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Discussion Overview

The discussion revolves around calculating the magnetic field strength of a simple bar magnet positioned on a plane at specific coordinates. Participants explore the complexities involved in deriving equations for the magnetic field, particularly in the absence of straightforward solutions for solid magnets compared to electromagnets.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant seeks equations to calculate the magnetic field strength at a point in relation to a bar magnet, expressing difficulty in finding relevant resources.
  • Another participant notes that the strength of a magnet is influenced by factors beyond just its size and material composition.
  • A different participant mentions the complexity of the problem, stating that there is no known analytical solution and suggests using approximations from established literature, specifically referencing Jackson's book.
  • The original poster acknowledges the complexity of the problem after further consideration and indicates a willingness to continue the discussion if more questions arise.

Areas of Agreement / Disagreement

Participants generally agree on the complexity of calculating the magnetic field strength for a bar magnet, with no consensus on a definitive solution or approach. Multiple views on the factors influencing magnetic strength are presented.

Contextual Notes

The discussion highlights limitations in available equations for solid magnets compared to those for electromagnets, as well as the need for approximations in the absence of analytical solutions.

Cheney
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If I have a simple bar magnet which is say 'w' x 'h' metres in dimension placed on a plane, say at cartesian coordinates (xM, yM), how can I work out the magnetic field strength at some arbitary point (x, y) also on that plane.



I've searched the internet but can only find equations to do with electomagnets or magnetism due to electic current. Nothing for a plane old chunk of iron.

I just need the equations, you can define the properties of the magnet such as how strong it is.

Thanks.
 
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The strength of a magnet is not defined by just its size and composition.

- Warren
 
It's not a trivial problem even though it looks like one. There's no analytical solution that I know of.
You can find the eqs. for the field of a homogenously magnetized sphere in Jackson's book (section 5.10), that might do as an approximation.
 
Thanks arcnets, I will check out the book. After looking at the problem some more I agree that it is far from trivial.

I'll post if I have any more questions.
 

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