Can metal shavings orbit around a wire in a magnetic field-free room?

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Discussion Overview

The discussion explores the behavior of metal shavings in relation to a current-carrying wire in a hypothetical gravity-free environment. Participants examine whether the shavings would orbit the wire in alignment with the magnetic field lines created by the current.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants assert that a magnetic field is generated around a wire when current flows through it, leading to the question of whether metal shavings would orbit the wire.
  • One participant proposes that iron filings would follow the magnetic flux rather than the current itself.
  • Another participant argues that iron filings would not orbit but would align with the magnetic field, taking on an induced dipole rather than exhibiting monopole behavior.
  • It is suggested that if the current remains constant, the filings would align with the magnetic field lines, potentially forming discrete rings around the wire depending on their initial spatial distribution.
  • Concerns are raised about the behavior of the filings if the current is changing, with uncertainty regarding how the induced currents in the filings would interact with the changing magnetic field.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of metal shavings in the presence of a magnetic field, with no consensus reached on whether they would orbit the wire or merely align with the field lines.

Contextual Notes

The discussion highlights uncertainties regarding the effects of changing currents on the behavior of metal filings and the assumptions about their initial distribution and symmetry.

Jules18
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When a wire has current running through it, a magnetic field is created around it, right? And I've seen lots of diagrams of the magnetic field lines wrapped around a wire in a coil-like fashion.

So, hypothetically, imagine if there was a current running through a wire, and that wire was suspended in a room that was free of any gravity.
Would metal shavings orbit around that wire in the same direction as the magnetic field lines?
 
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I think Iron filings would actually follow the magnetic flux rather than the current.
 
Jules18 said:
When a wire has current running through it, a magnetic field is created around it, right? And I've seen lots of diagrams of the magnetic field lines wrapped around a wire in a coil-like fashion.

So, hypothetically, imagine if there was a current running through a wire, and that wire was suspended in a room that was free of any gravity.
Would metal shavings orbit around that wire in the same direction as the magnetic field lines?

No, that's how you'd expect a magnetic monopole to behave, if one actually existed. An iron filing (for example) would take on an induced dipole, which would simply align with the field rather than "flying" around the flux loops.
 
If the current was held constant they would line up with the magnetic field lines, which would be closed circular loops around the wire. If the effect is to be noticeable this requires that the metal filings have some asymmetry. It's exactly the same effect produced when placing a permanent magnet in the vicinity of metal filings. Since every single filing gets magnetized they would attract each other, and therefore gather in lumps symmetrically placed around the wire. These could be very numerous resulting in a seemingly continuous circle. I think this might result in discrete rings forming, whose separation could be small. The net effect would be that you see contours of the field lines in the space not occupied by metal filings. It all depends on how the filings are spatially distributed before the magnetic field is applied.

If the current is changing I'm not entirely sure as of what exactly would happen. They wouldn't reflect the changing field at every instant of time, because the changing field induces a current in the filings, which in turns give rise to new magnetic field affecting the filings around it, and I can't tell the net effect. If the field is big enough it might overcome this induction effect and just move in accordance with the field changes.

Is there a simplifying principle I'm missing?
 

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