Core falling out of electromagnet

[lujacobs]

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

 

[mikeph]

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?

 

[lujacobs]

Is is not held in place machanically. It is just a solenoid with an iron core in it.

 

[mfb]

There is no easy formula to calculate this, and the geometry of the setup is important.

 

[lujacobs]

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.