Electron charge and spin creating a magnetic field?

[JuicyFruit123]

TL;DR Summary

Electrons are negative monopoles, but their spin creates an independent magnetic field. How?

From what I understand, electrons are negatively charged, however, I have recently come to learn that electrons also have a spin which creates a magnetic field around each electron. I don't understand how the electron can be a negative monopole, yet have a completely independent magnetic field and the two don't somehow interfere.

 

[Dale]

I don’t understand why you think being a monopole would interfere with having a magnetic field. Can you explain what bothers you about it?

 

[PeterDonis]

Electrons are negative monopoles

Of electric charge, not magnetic.

 

[Gordianus]

Perhaps the confusion arises from the fact the electron has "only" negative charge (electric monopole) whilst the magnetic spin is of dipole type.

 

[JuicyFruit123]

I don’t understand why you think being a monopole would interfere with having a magnetic field. Can you explain what bothers you about it?

Basically the electron as a particle is a negatively charged monopole. But it also has a magnetic field which creates a positive and negative charge on either end of the electron. Shouldn't the two interfere?

 

[PeterDonis]

Basically the electron as a particle is a negatively charged monopole.

An electric monopole. Not magnetic.

it also has a magnetic field which creates a positive and negative charge on either end of the electron.

Magnetic fields don't create electric charge. They create magnetic poles. The reason the electron has a magnetic field is that it has an electric charge and nonzero spin; this creates the magnetic field.

Shouldn't the two interfere?

Not at all; as above, they are all part of the same phenomenon, that the electron has an electric charge and nonzero spin.

 

[JuicyFruit123]

Oh I think I get it now. So the electron has a negative charge and when that charge moves (spin) it creates the magnetic field?

 

[Dale]

a magnetic field which creates a positive and negative charge on either end of the electron.

This part is simply a mistake. The magnetic dipole moment does not produce an electric dipole moment.

 

[Nugatory]

So the electron has a negative charge and when that charge moves (spin) it creates the magnetic field?

Not quite, although that’s a fine classical picture for a spinning charged object. The catch is that the quantum mechanical property called “spin” has nothing to do with classical rotation/spinning; the electron isn’t spinning around any axis. Instead the spin and magnetic moment are like the mass or the charge - just there because that’s how electrons are.

Now you might reasonably ask why we call it “spin” if that’s not what it is…. And the answer is historical. When physicists first discovered that electrons had a magnetic moment more than a century ago they had no previous experience with quantum objects, so they took the magnetic moment as evidence that an electron was a small charged object spinning on its axis - that was the only classical way of explaining it.

We eventually learned that quantum mechanical spin is a completely different phenomenon, but by then it was too late - the name stuck, somewhat like the way that some islands in the Caribbean are still called the “Indies” even though they have nothing to do with India.

 

[PeterDonis]

So the electron has a negative charge and when that charge moves (spin) it creates the magnetic field?

As @Nugatory said, that classical viewpoint isn't really correct for a quantum object like an electron; but the basic connection between electric charge, spin, and a magnetic field is still valid.

 

[jtbell]

the name stuck, somewhat like the way that some islands in the Caribbean are still called the “Indies” even though they have nothing to do with India.

And a lot of people called native Americans "Indians" (some still do) even though they're not from India.

 

[Nugatory]

And a lot of people called native Americans "Indians" (some still do) even though they're not from India.

Yes, and for most Americans that's the most top-of-mind example... I started with that one, then thought that the geographical example might play better worldwide. (I expect that we could have an entire long and entertaining GD thread about similar historical malaprops)

 

[hutchphd]

I live in Indiana. I must be really confused...