Electromagnetic Repulsion Power

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Discussion Overview

The discussion revolves around the behavior of an electromagnet created using a coiled wire and its interaction with a permanent magnet, specifically focusing on achieving electromagnetic repulsion. Participants explore the conditions under which repulsion can occur and the factors influencing the strength of the electromagnet, including the number of turns in the coil and the voltage applied.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes their setup with a coiled wire and an AA battery, noting that while the electromagnet can attract objects when an iron core is added, it cannot achieve repulsion against a permanent magnet.
  • Another participant suggests that increasing the number of turns in the coil and applying more voltage could enhance the strength of the electromagnet to achieve repulsion.
  • It is noted that the magnetic attraction of the permanent magnet to the iron core is stronger than the magnetic field produced by the electromagnet, leading to attraction rather than repulsion.
  • One participant proposes measuring the forces involved to better understand the interaction between the electromagnet and the permanent magnet.
  • There is a discussion about whether the repulsion force will always be weaker than the attraction force, with some participants agreeing that this is the case until the electromagnet is made stronger.
  • Another participant argues that the iron core, being passive, will align with the stronger magnetic field, resulting in a net force that is less than either of the individual magnetic forces.

Areas of Agreement / Disagreement

Participants generally agree that the current strength of the electromagnet is insufficient to achieve repulsion against the permanent magnet. However, there is no consensus on whether repulsion can ever exceed attraction without significantly increasing the electromagnet's strength.

Contextual Notes

The discussion highlights the dependence on the relative strengths of the magnetic fields involved and the passive nature of the iron core, which complicates the ability to achieve repulsion. There are unresolved questions about the specific conditions required for repulsion to occur.

Jakeeis
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So I coiled ~3' of 28awg wire in a 1/4" coil and connected it to an AA battery. It is unable to pick up nuts but still attracts and repulses in the presence of a permanent magnet. When a piece of iron is added to the center of the coil the strength of the magnet increases, as expected, and it is now able to pick up nuts. The problem is that now both poles of the permanent magnet are now attracted to the iron core. How can I achieve repulsion with the electromagnet? Would more turns or voltage help?

Thanks for your help!
 
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Jakeeis said:
The problem is that now both poles of the permanent magnet are now attracted to the iron core. How can I achieve repulsion with the electromagnet? Would more turns or voltage help?

Hi
and welcome to PF :)

yes many more turns and a few more volts...
At the moment the magnetic attraction of the permanent magnet to the iron core far exceeds the magnetic field strength of your electro magnet

cheers
Dave[/QUOTE]
 
Last edited by a moderator:
Jakeeis said:
How can I achieve repulsion with the electromagnet? Would more turns or voltage help?
The permanent magnet is obviously a lot stronger than your electromagnet so the induced magnetisation in the iron, due to the permanent magnet - and which will cause attraction, is stronger than any magnetisation that your electromagnet can produce. So the net resultant of the two magnets still causes attraction. If you could actually measure the forces involved, I am sure you would measure a smaller force with your electromagnet on 'repel' setting. You could use a small Force Meter or weak spring or you could even hang the iron on a string cradle and see if the angle it hangs at is altered with and without current flowing.
 
That makes sense. But does this mean that the repulsion force will always have a lower magnitude than the attraction force?
 
until you make the electromagnet stronger, yes
 
Thanks for your help!
 
Jakeeis said:
That makes sense. But does this mean that the repulsion force will always have a lower magnitude than the attraction force?
The Iron is passive and will take a 'polarity' which is due to the stronger of the two fields. So you will always have a field vector that is a product of the cancellation of the two fields you put it in. The resultant will always be less in magnitude than either of the two.
I don't think there is anything inherently asymmetrical about the situation you describe so your 'repulsion' term only means 'attraction' to the other (winning) magnet.
 

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