Can a magnetic field defy gravity?

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Discussion Overview

The discussion explores the possibility of using a magnetic field to counteract gravity, specifically in the context of iron filings placed on a cardboard. Participants examine whether a sufficiently strong magnetic field can make the filings hang in the air and discuss related concepts such as magnetic levitation and stability.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants propose that it is possible for iron filings to hang in the air against gravity with a sufficiently strong magnetic field.
  • Others argue that while it may be possible to attract the filings upwards to stay on the underside of the cardboard, achieving stable motionless levitation is not feasible due to the instability of passive magnetic levitation.
  • A participant mentions that toys demonstrating this effect require stabilization mechanisms, such as a clear plastic screen or spin stabilization.
  • One participant questions the reason behind the instability of passive magnetic levitation, prompting further inquiry into the underlying principles.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of achieving stable levitation of iron filings using magnetic fields. There is no consensus on whether it is possible to make them hang motionless in air.

Contextual Notes

The discussion references concepts such as Earnshaw's theorem, which may limit the understanding of magnetic levitation stability, but the implications of this theorem are not fully explored in the conversation.

shihab-kol
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If I keep iron fillings on a cardboard with a wire carrying current in some direction, I know that the fillings will orient in concentric circles.But what happens if I keep the fillings on the underside of the cardboard? Is it possible to make them hang in the air against gravity with a sufficiently strong magnetic field?
 
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Yes, it is possible. If I think the Magnetic force equals the pull of gravity.
 
shihab-kol said:
Is it possible to make them hang in the air against gravity with a sufficiently strong magnetic field?

have you not seen those toys that do that ?
America-Carlisleco-magnetic-font-b-levitation-b-font-font-b-pen-b-font-spin-freely-desk.jpg
SKU140192-500x500.png
Dave
 
shihab-kol said:
If I keep iron fillings on a cardboard with a wire carrying current in some direction, I know that the fillings will orient in concentric circles.But what happens if I keep the fillings on the underside of the cardboard? Is it possible to make them hang in the air against gravity with a sufficiently strong magnetic field?

Copernicus45 said:
Yes, it is possible. If I think the Magnetic force equals the pull of gravity.

It will not be possible to have them hang motionless in air, but it may be possible to have them attracted upwards such that they stay on the bottom side of the cardboard. The former isn't possible because passive magnetic levitation is unstable. Both of the toys shown in Davenn's post require something to stabilize them. I believe the clear plastic screen at the tip of the first toy stabilizes it and keeps it from moving forwards until it falls to the table, and I assume the 2nd toy is spin-stabilized, but I'm not certain.
 
Video showing a strong magnetic field picking up some rather large "filings"...
 
Drakkith said:
It will not be possible to have them hang motionless in air, but it may be possible to have them attracted upwards such that they stay on the bottom side of the cardboard. The former isn't possible because passive magnetic levitation is unstable. Both of the toys shown in Davenn's post require something to stabilize them. I believe the clear plastic screen at the tip of the first toy stabilizes it and keeps it from moving forwards until it falls to the table, and I assume the 2nd toy is spin-stabilized, but I'm not certain.
Why is passive magnetic levitation unstable?
 

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