I can find equations to give the force of an electromagnet on a piece of iron when the iron touches the electromagnet.
But what about when the iron is some distance from the electromagnet? Presumably the force depends on the shape/size of the iron piece as well as the location of the piece away from the magnet.
If anybody can tell me how to calculate this, even if I have to write a numerical calculation routine, I would appreciate any direction on this.
Best Answer
I believe you can approximate the iron as a collection of dipoles, and calculate the potential energy as $$\frac{1}{2} \int(MB)\rm{d}V$$ over the volume of the iron, where $M$ is the magnetization and $B$ is the total field. This becomes impossibly difficult with a nonlinear magnetic material and an asymmetrical magnet. As always, the gradient of potential energy gives force. Good luck.