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sooyeah

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Magnetics in relation to particles
« on: 21/09/2007 12:53:45 »
Can a particle carry a magnetic charge? I think its called a monopole.
So do these particles that carry a magnetic charge exist?


 

Offline Soul Surfer

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Magnetics in relation to particles
« Reply #1 on: 21/09/2007 14:35:00 »
Some of the theories of subatomic structure allow magnetic monopoles to exist and attempts have been made to detect them but none have been successful yet.  However if you think about how magnetism is created by having an electrical current running round a circle in a coil it is not possible to conceive the creation of one magnetic pole without at the same time creating the other.
 

Offline syhprum

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Magnetics in relation to particles
« Reply #2 on: 21/09/2007 16:13:41 »
What happens if you try to create a psuedo monoplole by assembling wedge shaped magnets into a sphere
 

Offline Soul Surfer

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Magnetics in relation to particles
« Reply #3 on: 21/09/2007 17:13:02 »
I see your point. A monopole might actually be a dipole with one of the poles hidden inside I've no idea what would happen.  I see no problems with making a hemispherical shell the magnetic field lines would be able to go through space from one pole to the other but pushing two identical hollow hemispheres together with opposing poles on the inside and outside would require a lot of force and may well cause the permanent magnetic field to be disrupted and cause an opposing pole break out on the surface of the sphere somewhere.  I reckon that is what would probably happen.  It would be quite an interesting experiment to try.

I am sure if you did it with a set of coils the fields would reverse in the gaps between the coils to complete the magnetic circuit and the field from the monopole would fade with an inverse cube law just like a dipole  The field from a true monopole should fade as an inverse square law.  I always thought thst the best pseudo monopoles are in fact very long bar magnets where the other pole is a long way from the experimental area.
« Last Edit: 21/09/2007 17:20:16 by Soul Surfer »
 

lyner

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Magnetics in relation to particles
« Reply #4 on: 21/09/2007 18:58:30 »
At School, it was explained to everyone that you can't get an isolated magnetic pole, and that a 'magnetic line of force' is the path that an isolated pole would take around a magnet (if it actually existed).
Having told us that, they then went on to do a very impressive demo in which a  long magnetised knitting needle was stuck through a cork and floated in a large glass trough full of water. When a bar magnet is held  at the  level of the top end of the needle , the top of the needle slowly moves around in a loop, from one pole to the other, along a curve - just like the  well known pattern of lines round a bar magnet.
I found it a bit confusing at the time.
 

lyner

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Magnetics in relation to particles
« Reply #5 on: 21/09/2007 19:05:29 »
On a technical point -  a magnetic dipole  is  produced by electric  charge flowing around a loop (this can be at an atomic level). You can't produce an true monopole  because all the magnetic field lines have to be continuous. The ones 'inside' your monopole would have nowhere to go. The harder you tried to squash  the  lines to make them behave as you wanted them to, the more force you would need, so you can't do it.
 But you can get there, 'near enough for jazz'. The knitting needle, above, gives the  lines, inside, a way out so the top end behaves more or less like a monopole.
 

Offline lightarrow

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Magnetics in relation to particles
« Reply #6 on: 21/09/2007 20:10:15 »
What happens if you try to create a psuedo monoplole by assembling wedge shaped magnets into a sphere
No field at all. For magnetic field div(B) = 0, so there is no net flux of B out of the sphere; since, because of spherical symmetry, the field B must be radial and with the same intensity in every point of the spherical surphace, the total flux is B4πR2 but this must be 0, so even B is zero.
 

Offline Atomic-S

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Magnetics in relation to particles
« Reply #7 on: 24/09/2007 07:43:15 »
That is correct. It is an inevitable consequence of the principle that magnetism arises solely, insofar as is yet known, from charge in motion. The more profound question, as to whether magnetic monopoles might possibly exist in some state of matter unfamiliar to us, still remains intriguing. I do not know that anyone has ever been able to prove conclusively that it is impossible. An interesting evidence that it might be possible lies in the fact that it is possible to rewrite Maxwell's electromagnetic equations in such a way that there is complete symmetry between the scale and behavior of electricity and magnetism, except for the one detail that the value of magnetic charge must be zero . However, these rewritten equations easily accomodate a value different from zero, if such were ever discovered.  As to why it has not been found, that seems to lie deep within the mysteries of subatomic structure. Perhaps the following observation may be of interest in re this:  Everything we know about ordinary matter tells us that negatively charged particles orbit positively charged nuclei. The question arises whether the reverse might be true. As it turns out, the reverse can indeed be true -- such a situation is called antimatter.  Antimatter has actually been discovered, although it is rare in the known universe. It still is quite a mystery why antimatter is so rarely encountered, even though its possible existence is now clearly demonstrated. Could something like that be true of magnetic monopoles? It might lead to atoms composes of north-magnetic nuclei being orbited by south-magnetic particles. That would be a state of matter niether matter nor antimatter, but something else.  What does quantum physics tell us about the possibility of something like this?  I haven't the answer, but one thing we do know is that the transformation of matter to antimatter is equivalent to the reversal of an odd number of space-time dimensions of the system.  Space and time have something to do with it. What manipulation of space-time might create magnetic monopole matter?  Maybe somebody out there knows.
 

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Magnetics in relation to particles
« Reply #7 on: 24/09/2007 07:43:15 »

 

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