magnetic monopole.

[neptune]

I do not know much about magnets, but I read somewhere that a magnetic monopole is the holy grail that everyone is looking for. What if you made an extremely long bar magnet, say 3 metres long. The poles would be so far appart as to be virtually isolated monopoles. Is there a theoretical limit to the length of a magnet? It could be magnetised by a very long coil, or stroking it with a magnet. This would give you lots of exercise!

[Michelinho]

Hi neptune,

I am on shaky ground here but I think it would soon develop multiple alternating poles all along the bar as the field would be too weak to travel from one end to the returning point at the center of the bar.

Take care,

Michel

[Low-Q]

I do not know much about magnets, but I read somewhere that a magnetic monopole is the holy grail that everyone is looking for. What if you made an extremely long bar magnet, say 3 metres long. The poles would be so far appart as to be virtually isolated monopoles. Is there a theoretical limit to the length of a magnet? It could be magnetised by a very long coil, or stroking it with a magnet. This would give you lots of exercise!

Hi,

These two poles will have magnetic lines traveling from north to south in all imaginable agles. The monopole is a circular magnetic field that exists in only one angle. There is no defind north and south. This monopole can be obtained by a conductor with current flowing through it. The magnetic lines will allways circulate around the wire directly angular to the direction of the current, and not spread out in all possible directions.

In a bar-magnet you also have a sort of current flowing as there is a lot of atoms where the electrons are spinning in more or less in the same direction, but the magnetic field around it isn't following the same direction - in parallell as around a conductor. They are instead trying to escape from eachother side by side by spreading out in all directions and encircles the barmagnet. That is the key why permanentmagnets can't be used as a monopole, or to make working permanentmagnet motors.

On the other hand, nor two monopoles would work together as a magnet motor. They will either attract or repell eachother from all sides depending on the circular magnetic direction.

Br.

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