Force on conductor carrying currentsurrounded by solid magnetic material

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Discussion Overview

The discussion revolves around comparing the forces experienced by a current-carrying conductor placed in different configurations within magnetic fields. Specifically, it examines the scenarios of a conductor in air versus one in a cylindrical cavity surrounded by magnetic material, focusing on practical calculations and theoretical implications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Participants inquire about the equations applicable to the force on a conductor in air surrounded by a magnetic field.
  • Clarification is sought regarding the geometry of the second case involving a cylindrical cavity with electrical insulation.
  • One participant suggests that the force in the second case may be significantly lower than in the first case, possibly approaching zero.
  • Another participant emphasizes the shielding effect of magnetic materials, suggesting that the conductor in the cavity would experience minimal to no magnetic field, resulting in a small force.
  • A participant mentions the design of an electric motor that utilizes a similar configuration, indicating practical applications of the discussed concepts.
  • Questions arise regarding the values of relative permeabilities for various magnetic materials and their impact on the force experienced by the conductor.

Areas of Agreement / Disagreement

Participants express differing views on the force experienced by the conductor in the two scenarios, with some suggesting that the force in the cavity may be negligible due to the shielding effect of the magnetic material. The discussion remains unresolved regarding the exact calculations and implications of the configurations.

Contextual Notes

Participants have not reached a consensus on the specific mathematical formulations or practical values for the scenarios discussed. The conversation includes assumptions about the configurations and the behavior of magnetic fields in the presence of magnetic materials.

Who May Find This Useful

This discussion may be of interest to those involved in experimental physics, electrical engineering, and the design of electromagnetic devices, particularly in understanding the effects of magnetic materials on current-carrying conductors.

djsourabh
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i want to compare force on current carrying conductor ,
1)placed in air surrounded by magnetic field
2)placed in the cylindrical cavity(without air gap but some electrical insulation) which is placed in magnetic field.
please give me practically calculated answers with calculations.
 
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djsourabh said:
i want to compare force on current carrying conductor ,
1)placed in air surrounded by magnetic field
2)placed in the cylindrical cavity(without air gap but some electrical insulation) which is placed in magnetic field.
please give me practically calculated answers with calculations.

Well, do you know the equation to use for your case #1? It's a common equation:

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/forwir2.html

And for your case #2, could you maybe clarify a bit about the geometry? Is there some application that you have in mind? I think I know the answer, but need a few more details before commenting about the force for case #2...
 
berkeman said:
Well, do you know the equation to use for your case #1? It's a common equation:

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/forwir2.html

And for your case #2, could you maybe clarify a bit about the geometry? Is there some application that you have in mind? I think I know the answer, but need a few more details before commenting about the force for case #2...

i meant ,how much times is the force for case 2 that of case 1?
 
djsourabh said:
i meant ,how much times is the force for case 2 that of case 1?

Negative infinity (or zero, depending on how you write the fraction) most likely. But that's why I asked for more information about the configuration of case #2. Can you provided a sketch?

What is the context of your question? Is it a thought experiment, something for schoolwork, or somthing that you want to build and test?
 
i want to build & test it.
can you provide mathematical or logical explanation for your answer ?
take sketch as
there are 2 poles of magnet separated by a distance.in between them space is filled by magnetic material .
it contains cavity having conductor carrying current.
can you give me the formula and practical answer for above scenario?
what are values of relative permeabilities for magnetic materials?
 
Last edited by a moderator:
djsourabh said:
i want to build & test it.
can you provide mathematical or logical explanation for your answer ?
take sketch as
there are 2 poles of magnet separated by a distance.in between them space is filled by magnetic material .
it contains cavity having conductor carrying current.
can you give me the formula and practical answer for above scenario?
what are values of relative permeabilities for magnetic materials?

(Please do not use text speak like "u" and "ur" here on the PF. It is against the rules. I have fixed up your post above).

The cavity in the magnetic material is shielded from the external B-field. That's what magnetic materials do -- they concentrate and divert magnetic fields. So the wire in the cavity will experience very little or zero magnetic field, and there will be a correspondingly small force on it.
 
ZenonDorin said:
My new electric motor is based on exactly this thing (part of the coil is in the cavity of a permalloy).

https://www.physicsforums.com/showthread.php?t=663657

I skimmed the video, but was not able to quite understand what is going on (I'm at work and cannot spend much time viewing it). Is there supposed to be audio that goes with the video?

But if you have permalloy surrounding some of your wires, they will not have much force applied to them because of the shielding effect.
 
berkeman said:
I skimmed the video, but was not able to quite understand what is going on (I'm at work and cannot spend much time viewing it). Is there supposed to be audio that goes with the video?

But if you have permalloy surrounding some of your wires, they will not have much force applied to them because of the shielding effect.

Yes, you cannot understand without audio.

That's the key. On a certain portion there must be no electromagnetic force, else the integral of force on the entire coil would be 0.

No matter how you place the magnet or the coil, without such shielding or without current switching (with an electronic speed controller or brushes), there can't be any continuous rotation which is required in an electric motor.
 
  • #10
so, in which material medium the force on current carrying conductor will be highest?
(consider above configuration)
 

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