Magnetizing an electrical conductor made of a magnetizable material?

[Low-Q]

Hi @all,

I have wondered about one thing for quite long time now:

We know it is possible to permanently magnetize objects with a strong permanent magnet or with an electromagnet.
We also know that an electric conductor creates a circular magnetic field around it when current flows in it.
What if the wire was made of a material which is possible to magnetize.
Then we add som DC-current through it so it generate a magnetic field around this wire.
The atoms should then be orientated accordingly.

Will this circular magnetic field remain as a function of magnetization of the wire after we shut of the DC-current?

Wouldn't the atoms be orientated in one direction - the same as when there was DC current flow going through it?

If yes: it should be possible to put this wire in a magnetic field and get work.

If not: why can't a magnetizable electric conductor store magnetism like that?

br.

Vidar

[Steven Dufresne]

Hi Vidar,
Yes, the magnetic field will remain after the DC is shut off. I inadvertantly did this with the steel ferromagnetic wire sectors on the disk of my small testatika machine.

The magnetic field would have to be moving though, in order to get work out of it. So after you turn off the DC current all you have is a wire-shaped permanent magnet.
-Steve
http://rimstar.org   http://wsminfo.org

[jadaro2600]

If not: why can't a magnetizable electric conductor store magnetism like that?

Current has a tendency to flow across the outside of a conductor along it's surface.  As a result, a wire which could become a permanent magnet may not be all that it could be due to variation in its current path.  Heat causes a magnetic field to become destroyed - current causes heat.

Considering the above, a magnetic wire, as you have described, would have to be kept cold in order for it to maintain an electromagnetic field while continuing to have current flowing through it - otherwise the material undergoes hysteresis and the field begins to collapse or the material heats up - and then destroys what the original magnetic field was.

Will this circular magnetic field remain as a function of magnetization of the wire after we shut of the DC-current?

Yes and no.  Most magnetization is done through a proprietary method of pulsing, heating, sintering, pulsing, and then finally cooling in a strong mag field or something to that effect.

The idea is that the magnetic material will be just as inclined to it's own field ans it would be to change conforming to another - it's about the amount of resistance to change that the wire would withstand.

If you could get your wire to be a magnet, then it would be just like any other magnet in the shape of a wire.  Why not use a current and have it be the same?

[Koen1]

Yes, an iron wire should be easier to magnetise when it is hot;
current running thrugh the wire while it cools down should cause this
circular magnetisation, and if the current is removed and the wire
not re-heated the wire should maintain a degree of remanent magnetisation.

But, as stated above, this will not induce any current as the induction
of current requires a change in magnetic field, not a static magnetic field.

If you now send an opposing current through the wire, it should experience
the remanent magnetic field as opposing its own, and this should have
a dampening effect on the current untill the remanent field is overcome by
the new current's induced field. So it should cost a little more current to
demagnetise again.
This could in theory be used as a crude form of "diode" in that input currents
that are in alignment with the remanent magnetic field should experience
less resistance than currents whose magnetic field are opposed to that of the wire.
So not really a diode but rather a lower resistance in one direction than in the other.
Still, the hotter the wire gets, the less it maintains its magnetisation, so the more we
pulse the wire, the faster the effect diminishes.

regards,
Koen

[Low-Q]

Current has a tendency to flow across the outside of a conductor along it's surface.  As a result, a wire which could become a permanent magnet may not be all that it could be due to variation in its current path.  Heat causes a magnetic field to become destroyed - current causes heat.

Considering the above, a magnetic wire, as you have described, would have to be kept cold in order for it to maintain an electromagnetic field while continuing to have current flowing through it - otherwise the material undergoes hysteresis and the field begins to collapse or the material heats up - and then destroys what the original magnetic field was.
Yes and no.  Most magnetization is done through a proprietary method of pulsing, heating, sintering, pulsing, and then finally cooling in a strong mag field or something to that effect.

The idea is that the magnetic material will be just as inclined to it's own field ans it would be to change conforming to another - it's about the amount of resistance to change that the wire would withstand.

If you could get your wire to be a magnet, then it would be just like any other magnet in the shape of a wire.  Why not use a current and have it be the same?

Where the curent flows depends on frequency. A flat foil wire which have much greater surface than a round wire with same area in its cross section, does not conduct better than the round one. That proves that current at DC is flowing as much inside the wire as outside. However, at very high frequencies, the flat foil wire conducts better than the round one.

Current causes heat depending on the voltage drop over that conductor (All conductors have its own resistance to current). If no voltage drop the current can go as high as possible imaginable without any heat at all. Watt is amps times voltage. No voltage, no watt, or energy.

The wire would be magnetized circular as the current is flowing along the wire and not in circles of its cross section.

Anyways, I have made a model in FEMM. I used a round magnet in a closed loop so I got a circular magnetic field inside the magnet. The idea was to se what happens inside this magnet if another magnet pole came near it. I can see that the magnetic lines is compressed at one side and expanded on the other side, just in the same ways as a magnetic field around a wire is doing. But with a wire I could get force in the direction towards the less densed magnetic field, but with my model of the round magnet with circular magnetic field, did not get any force at all.

Attached there is a picture showing the model.