Getting the magnetic field as a function of current

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Discussion Overview

The discussion revolves around the relationship between electric current and the magnetic field generated by an electromagnet, particularly in the context of solving Maxwell's equations. Participants explore theoretical and practical aspects of this relationship, including the effects of circuit components and materials.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the general relationship between current and the magnetic field, specifically seeking a function B(x,y,z,t,I).
  • Another participant suggests that experimentation could provide insights, noting that Jackson's text may not be beginner-friendly and recommending Hyperphysics as a more accessible resource.
  • A participant mentions that the relationship is generally linear according to established equations but highlights that computations are often limited to specific areas where integrals are easier to solve.
  • Concerns are raised about complications arising from the presence of ferromagnetic materials, including nonlinearity, hysteresis, and time dependence, with references to additional concepts such as permeability and eddy currents.
  • One participant shares a link to a simulation software that could help model the magnetic circuit in a more comprehensive manner.
  • Another participant reflects on the simplicity of a previously shared link after reconsidering the original question.

Areas of Agreement / Disagreement

Participants express varying viewpoints on the complexity of the relationship between current and magnetic field, particularly regarding the effects of different materials and the applicability of theoretical models. There is no consensus on a definitive answer or approach.

Contextual Notes

Limitations include the dependence on specific conditions such as the presence of ferromagnetic materials, which introduce nonlinearity and other complexities. The discussion also acknowledges that theoretical models may not fully capture practical realities.

Who May Find This Useful

This discussion may be of interest to those studying electromagnetism, particularly in the context of circuit design and the behavior of magnetic fields in various materials.

vogtster
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Howdy,

So, I'm curious, is there a general relationship between current input into an electromagnetic and the magnetic field that it generates in space? The trivial example is wrapping a wire around a rod, then sending a current through it which causes a magnetic field.

My set up is a simple circuit, where we have a power supply, resistor, and electromagnet. I want to solve maxwell equations, and I want to find the relationship between B and I, that is B(x,y,z,t,I).

I have Jackson, so if someone could refer me to an area in his book which may explain this, or any other sources I would appreciate it.
 
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vogtster said:
My set up is a simple circuit, where we have a power supply, resistor, and electromagnet
So why ask? Experiment !

Jackson isn't very introductory. Hyperphysics is a lot friendlier...
 
It's may be difficult...
according to general equations it's linear relationship(like here: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/solenoid.html or here: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html)

notice that usually all the computes are in specific area of the space, usually where the integral is easy to solve...
If you want to simulate your magnetic circuit(everywhere in space) you can use this software: http://www.femm.info/wiki/HomePage

but always remember: "In theory there is no difference between theory and practice. In practice there is." and as I saw, especially in elctromagnets there is big difference
 
If there's ferromagnetic material involved you have some complications
its nonlinearity, google permeability
its memory google hysteresis , retentivity
its time dependence google Barkhausen
its own reaction to magnetic field google eddy current, retardation of magetization , magnetorestriction

Bozorth kinda 'wrote the book' on Ferromagnetism

.................

my two cents, and probably it's overpriced at that.
 
Last edited:

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