# Can a Neodymium Magnet be used as an electromagnet?

1. Nov 25, 2012

### jonymasterchf

Hi,
I would like to know if Neodymium Magnets can be used as an electromagnetic magnet. The idea is to get a Neodymium Magnet and add DC voltage to do the Gauss Law.
The college project is make a very powerful electromagnet, so I thought adding the most powerfull magnet and the some DC voltage would be able to make a very strong electromagnet.

Please correct me if I am wrong, I've been reading about the cautions of using Neodymium Magnets and also that they have 4 poles, so that is what confuses me.

2. Nov 25, 2012

### Staff: Mentor

How do you want to "add DC voltage"? With a coil around the magnet? If that gives a stronger magnetic field, you don't need the magnet. If not, it is not an electromagnet.

Depends on the magnet.

3. Nov 25, 2012

### jonymasterchf

But wouldn't be more powerful? Could you control the magnet field? Like turn it on and off.

4. Nov 25, 2012

### Staff: Mentor

It is a permanent magnet - if your applied external field is very strong and in the opposite direction, you can remove its magnetization, but then there is no point in using neodym magnets (its magnetic field won't come back on its own).

5. Nov 25, 2012

### streeters

This. Steel cores are used because they have very low remanence and coercivity. NdFeB magnets would need very high energy to demagnetise.

6. Nov 25, 2012

### OmCheeto

A 4 pole magnet?

I have 385 neodymium magnets. They are all of the two pole variety.

I suppose it is possible to make a 4 pole solid magnet, but I think it would be much easier to just glue them together.

7. Nov 27, 2012

### Enthalpy

The field added by an extra current would have the direction that makes the permanent magnet, hence no risk to de-magnetize it. But it has serious drawbacks:

- Polar pieces have an induction at saturation around 2T (1.9T for transformer laminations, 2.1T for pure iron, 2.3T for expensive iron-cobalt). Up to this induction, you consume current only to jump over the air gap, but very little to close the magnetic path through the iron.

- Nd magnets give some 1.1T with no added current, but between 1.1T and 2T they act essentially as an air gap. Their thickness is much more difficult to bridge through amps*turns than the same thickness of iron.

- So you would need to concentrate the flux of the permanent magnets to make sense, and use no current at all. Nd gives the best effect at 0.6T hence you can triple the induction in the iron core, by letting several magnets converge to the assembly's pole.

- But then you get a huge permanent magnet, something really dangerous - more so than an electromagnet that you can switch off.

By the way, I understood "produce a strong induction in a significant experiment volume". If your aim is "attract heavy iron parts" the task looks different.