Core falling out of electromagnet

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Discussion Overview

The discussion revolves around the mechanics of levitating an iron core within an electromagnet. Participants explore the calculations needed to determine the minimum current required to keep the core suspended and the relationship between current and core position.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks to calculate the minimum current needed to prevent the iron core from falling out of the electromagnet.
  • Another participant questions the premise, suggesting that the core is magnetized by the current and held mechanically, implying that it should not fall out.
  • A different participant asserts that the core is not held mechanically, indicating that it is simply a solenoid with an iron core.
  • One participant notes the complexity of the situation, stating that there is no straightforward formula and that the geometry of the setup is significant.
  • A participant provides specific dimensions of the solenoid and core, along with the number of turns in the coil, and approximates the core's permeability, indicating a need for a formula to determine the current at which the core will fall.

Areas of Agreement / Disagreement

Participants express differing views on whether the core is mechanically held in place or not, leading to a lack of consensus on the core's behavior within the electromagnet. The discussion remains unresolved regarding the calculations and principles involved.

Contextual Notes

Participants mention the importance of geometry in the calculations, and there is uncertainty regarding the permeability of the core, which may affect the outcomes of the proposed calculations.

lujacobs
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Hello,

I'm trying to levitate the iron core of an electromagnet at a certain postion. How can I calculate what the minimum currennt is that I need to put on the electromagnet to prevent the core from falling out at the bottom?

Is there an equation to know at what position the core will be if I put more current on it?

Thanks
 
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I'm not sure I understand this. The core of an electromagnet is magnetised by the current solenoid, and is held in place mechanically. Why would it fall out and what would stop it?
 
Is is not held in place machanically. It is just a solenoid with an iron core in it.
 
Last edited:
There is no easy formula to calculate this, and the geometry of the setup is important.
 
The outer diameter of the solenoid is 38mm, the inner diameter is 14mm.
The diameter of the core is 12.5mm. Both are 70mm long.
The number of turns on the coil is 335.
I don't know what the permeability of the core is, but I approximate it at 10000*mu_0. But I can verify this experimentally, when I know the correct formula for the current at which the core will fall.
 

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