Magnets

[Moontanman]

What would happen if you made a bunch of magnets shaped like spikes and when you put (glued with super glue) them together they formed a sphere with the south pole at the center of the sphere and the north pole on the surface? How would such a magnet look with it's magnetic field?

[Robittybob1]

What would happen if you made a bunch of magnets shaped like spikes and when you put (glued with super glue) them together they formed a sphere with the south pole at the center of the sphere and the north pole on the surface? How would such a magnet look with it's magnetic field?

So each magnet is cone (wedge) shaped to begin with. I would think a wedge shaped magnet has lost some of its magnetic field in the process of producing that shape.

Edited August 4, 2015 by Robittybob1

[John Cuthber]

You could make the metal wedge-shaped then magnetise it; that's not the problem.

The problem is that it doesn't work.

[Moontanman]

You could make the metal wedge-shaped then magnetise it; that's not the problem.

The problem is that it doesn't work.

 

 

Can you elaborate on that John?

[swansont]

You could make the metal wedge-shaped then magnetise it; that's not the problem.

The problem is that it doesn't work.

 

I think that's why you wouldn't be able to magnetize it after you made the wedges. It doesn't work that way.

 

———

 

The field from the interior would make it out to connect with the N poles on the outside. It's not going to look like a monopole.

 

Look at the bottom of this page at the arc magnets magnetized on their inner and outer face. That might help.

https://www.kjmagnetics.com/magdir.asp

[Robittybob1]

So each magnet is cone (wedge) shaped to begin with. I would think a wedge shaped magnet has lost some of its magnetic field in the process of producing that shape.

I was thinking if a bar magnet was machined down to the wedge shape, each piece of the original magnet removed would reduce the strength of the magnet.

I can't see any reason why each wedge shaped segment couldn't be still magnetized but what happens when the segments are all fitted together? Logic seems to say that one side will cancel out the opposite side so I'm picking that the sphere will not be an effective magnet.

Edited August 5, 2015 by Robittybob1

[swansont]

Logic seems to say that one side will cancel out the opposite side

 

 

Ever push two like poles together? Does it seem like there is a cancellation of the field?

[Moontanman]

 

I think that's why you wouldn't be able to magnetize it after you made the wedges. It doesn't work that way.

 

———

 

The field from the interior would make it out to connect with the N poles on the outside. It's not going to look like a monopole.

 

Look at the bottom of this page at the arc magnets magnetized on their inner and outer face. That might help.

https://www.kjmagnetics.com/magdir.asp

 

 

I didn't really expect it to look like a monopole but your link didn't help much since it didn't show an magnetic pole enclosed by another. I really have no expectations on this, just a mental exercise I cannot get a handle on, the best guess I can come up with is canceling each other out but that can't be right.

[John Cuthber]

Each wedge shaped bit of metal could be magnetised after it was cut to shape, but before assembly into a sphere.

And it still wouldn't help.

 

Imagine the lines of force round the magnet. As you put the next magnet near it the lines of force round each one still have to go from one end of the magnet to the other.

So, once you assemble the whole sphere what you have is a bunch of magnets each with a closed loop of field round them and practically no external field.

[Robittybob1]

 

 

Ever push two like poles together? Does it seem like there is a cancellation of the field?

Yes you can push them together but what has that done to the combined strength of the overall combination? I predict that the combined magnet will have reduced strength at the non touching poles.

[swansont]

Yes you can push them together but what has that done to the combined strength of the overall combination? I predict that the combined magnet will have reduced strength at the non touching poles.

 

Filed lines have to loop around and connect. You can't cancel one and leave the other intact.

[Robittybob1]

 

Field lines have to loop around and connect. You can't cancel one and leave the other intact.

I haven't got two bar magnets to test it, but wouldn't it be like an electromagnet made with dual windings each in opposite direction.

It the current is applied to either circuit the solenoid would become magnetized (but with opposite polarity) so when the current is simultaneously applied to both circuits would one field cancel the other?

Edited August 6, 2015 by Robittybob1

[swansont]

I haven't got two bar magnets to test it, but wouldn't it be like an electromagnet made with dual windings each in opposite direction.

It the current is applied to either circuit the solenoid would become magnetized (but with opposite polarity) so when the current is simultaneously applied to both circuits would one field cancel the other?

 

No, it's not like that. You can't put two physical magnets into the same space. Even in the electromagnet scenario, you don't lose some N pole field while keeping S pole field intact — the whole thing cancels, because you are reducing/canceling the net current.

 

Magnetic field lines loop around on themselves. You either have the loop, or you don't.

[Robittybob1]

 

.....

 

Magnetic field lines loop around on themselves. You either have the loop, or you don't.

I'd agree with that logic. Only issue that I'd raise is that when you push two magnets together you can't tell if some of the field lines are being cancelled. Obviously most of them aren't for the like poles are still repelling.

[swansont]

I'd agree with that logic. Only issue that I'd raise is that when you push two magnets together you can't tell if some of the field lines are being cancelled. Obviously most of them aren't for the like poles are still repelling.

 

My point is that they can't cancel at one end but not the other. You can't cancel only part of a field line. So if they don't cancel at one end, they don't cancel at the other.

[Robittybob1]

 

My point is that they can't cancel at one end but not the other. You can't cancel only part of a field line. So if they don't cancel at one end, they don't cancel at the other.

This is my simple understanding. Each atom in the material has a magnetic field. I understand it is the alignment of these molecular fields that ultimately produce a magnet. So a piece of iron starts off with the same number of atoms, and it becomes magnetized by some method. I think it depends on the degree of alignment at the atomic scale that will determine the strength of the magnet.

So is it fair to say one can never cancel a field line but one can alter the combined nature of the field lines.

[swansont]

This is my simple understanding. Each atom in the material has a magnetic field. I understand it is the alignment of these molecular fields that ultimately produce a magnet. So a piece of iron starts off with the same number of atoms, and it becomes magnetized by some method. I think it depends on the degree of alignment at the atomic scale that will determine the strength of the magnet.

So is it fair to say one can never cancel a field line but one can alter the combined nature of the field lines.

 

Right.

 

The reason a pair of electromagnets with opposite currents won't have a field is because the field generated by each wire segment will loop around and end on the wires that are next to each other, so there is no field that is in the interior or exterior of the coils. But the lines never cancel, as such.