B Magnetic Field & Particle Spin: Does It Matter?

AI Thread Summary
The discussion centers on whether the magnetic field generated by moving charged particles, such as protons or lithium nuclei, is influenced by the particles' spin values. It raises the question of whether magnetic fields arise from aligned spins or the current produced by moving charges. While traditional physics attributes magnetic fields primarily to moving charges, the relationship between charge and spin complicates this understanding. The conversation also touches on the role of neutrons, which possess spin but lack charge, suggesting they do not generate magnetic fields in the same way. Overall, the dialogue explores the potential for a more nuanced view of magnetic fields as possibly being better described in terms of spin.
synch
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Does the magnetic field caused by moving particles depend on the particle spin value?
Eg a stream of say protons spin 1/2 is creating a magnetic field. If the particles are (say) lithium nuclei spin 3/2 instead, does that create the same strength field ? (same conditions of course)
 
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synch said:
Eg a stream of say protons spin 1/2 is creating a magnetic field.
Do you think that this magnetic field arises from the, presumably, aligned spins of the protons in the beam or from the current generated by the moving charged particles?
 
[Will the spins be aligned in a weak field? .]

The standard logic goes, magnetic fields are typically created by moving charge, and so on. But charge always seems to be associated with spin, so there is also spin involved. Hence my question regarding using changed spin .
In general I am wondering if a magnetic field might be better described as a spin field - it makes more sense to me at least, ( qualitatively). That would maybe make the classical "lines of force" more sensible as directrices of resultant force or similar.

This might be better at the intermediate level, - it is long time since I did physics, hopefully it is a sensible question :)
 
synch said:
[Will the spins be aligned in a weak field? .]

The standard logic goes, magnetic fields are typically created by moving charge, and so on. But charge always seems to be associated with spin, so there is also spin involved. Hence my question regarding using changed spin .
In general I am wondering if a magnetic field might be better described as a spin field - it makes more sense to me at least, ( qualitatively). That would maybe make the classical "lines of force" more sensible as directrices of resultant force or similar.

This might be better at the intermediate level, - it is long time since I did physics, hopefully it is a sensible question :)
Technically the spin of an electron is quantum mechanical. If we treated the electron classically, then in the rest frame of the electron we would have the electromagnetic field associated with a spinning ball of charge. Which we could transform to the frame in which the electron is moving.

I'm not sure of the qualitative significance of the spin in this case. And, of course, the magnetic dipole moment of the electron is twice that calculated from classical electrodynamics. See, for example:

http://hyperphysics.phy-astr.gsu.edu/hbase/spin.html
 
synch said:
But charge always seems to be associated with spin, so there is also spin involved.
Not always. Neutrons have spin but they have no charge. As far as I know, there are no magnetic fields associated with neutron beams.
 
kuruman said:
Not always. Neutrons have spin but they have no charge. As far as I know, there are no magnetic fields associated with neutron beams.
In classical EM, the neutron should have no magnetic dipole moment (at least if we consider it as an elementary particle). But in the quark model, it does have a measurable magnetic dipole moment.
 
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