Question about the properties of electromagnetic fields

[Bararontok]

I recently posted a comment about the properties of electromagnetic fields in an article about electric fields in the library. But it was deleted, could someone please point out the errors in the article so I can refine my understanding of this phenomena?

The article is written below and corrections are greatly appreciated:

Electric and magnetic fields are both components of field particles called photons surrounding charged particles such as the electron. These fields vary with time because the charged particles are spinning and this spinning motion also causes the fields surrounding the particles to spin, making the field a time varying field. The generation of magnetic field lines in an inductor is caused by the spin of electrons passing through the electrical conductor. These field lines are generated by placing spinning electrons side by side by coiling the conductor. Because the spinning electrons are all spinning in the same direction, the force of the photons from one spinning electron will add to the force of photons from another spinning electron beside it and this will cause the photons to be shared by the electrons and force them to circulate around the entire series of spinning electrons generating concentrated magnetic field lines around the inductor.

 

[bapowell]

Just about everything in that paragraph is patently false. Rather than pointing out errors in this paragraph, your understanding of the phenomena would be aided best by obtaining an introductory physics textbook and flipping to the chapter about electromagnetic fields.

 

[Meir Achuz]

Take the book back to the library, or better, just lose it.

 

[Bararontok]

After researching a physics textbook on quantum electrodynamics, I think my biggest errors were how I poorly phrased my statements which leads to quite a confusing explanation on the behavior of the electromagnetic field.

The electromagnetic field is a force field that surrounds electrically charged particles. It is one of the four fundamental forces and it is mediated via the photon which is the quantum of the electromagnetic force.

Now the other question is what generates a time varying electromagnetic field? Is it the spin of an electrically charged particle, the movement of photons in the electromagnetic field, the movement of an electric current through a conductor, or the movement of an alternating electric current through a conductor?

Lastly, how are varying magnetic field lines generated in an inductor, is it because the net forces of electrons spinning in the coils of the inductor add together to amplify their magnetic fields and combine into a larger magnetic field?

I will use the image below that I found on google to better illustrate my point:

[PLAIN]http://img641.imageshack.us/img641/308/inductor.png

In the illustration there are magnetic field lines circulating around the inductor, now I was thinking that the spinning of the electrons within the inductor might generate the circulating magnetic field lines because the force of one spinning electron's field is added to the other which increases the magnetic field strength, but of course the magnetic field will counteract the change in current which will increase the resistance of the inductor and that is why inductors with more turns require a higher applied voltage. Is this correct or is there another way of interpreting the image?

 

[bapowell]

Electromagnetic radiation (time varying EM fields) is generated by an accelerated charge. It's the charge -- not the spin -- that's relevant to electromagnetism. And it's the acceleration that distinguishes radiation from the EM fields of static charges. Having read a book on QED, you should be aware that elementary particles, like electrons, don't actually spin about an axis. Your best bet is to begin researching the notion of 'real' and 'virtual' photons -- the former make up classical radiation while the latter can be understood as making up the fields of static charges.

 

[Bararontok]

Alright, so that means that it is the acceleration of a charged particle that causes a time varying electromagnetic field and that a stationary charged particle would have static electric and magnetic fields.

So when virtual photons circulate as magnetic field lines in an inductor powered by a direct current which has a constant polarity and flow rate, the magnetic field is considered to be time invariant because the electric charges giving rise to the field are not being accelerated. But when the current is an alternating current and there is an acceleration of charge due to the sudden reversal of current polarity, the inductor generates a time varying magnetic field which could be used to transmit radiation. Come to think of it, in radio transmitter designs that I have studied, the inductor is actually a form of radio transmitter.

Now, for my last question, what causes the magnetic field lines in a permanent magnet or DC powered inductor to circulate giving the magnet a positive and negative polarity? Is it caused by the momentum of electrons all spinning or revolving in one direction which imparts directionality to the circulation of the magnetic field lines? In an article I read in wikipedia, the static time invariant magnetism is the product of the spins and revolutions of the electrons in a material, aligning together which causes them to share virtual photons and generate a more massive magnetic field. In a normal material, these spins and revolutions cancel out due to the fact that they are not aligned. The source material runs close to my explanation and it can be read below:

[PLAIN]http://img839.imageshack.us/img839/1663/magnetz.png

 

[bapowell]

A spinning electron is like a tiny dipole. If you have a bunch of electrons all with their spins aligned, then you get a material that has the properties of one big dipole -- a magnet.

 

[Bararontok]

That is precisely what I said earlier about electrons in inductors. Because their spins are aligned and concentrated when passing though a coil, a larger magnetic field is generated as the result of smaller magnetic field forces adding to generate a net force.

 

[bapowell]

That is precisely what I said earlier about electrons in inductors. Because their spins are aligned and concentrated when passing though a coil, a larger magnetic field is generated as the result of smaller magnetic field forces adding to generate a net force.

OK, sorry I missed that. However, it's not correct to say that the spinning electron imparts any sort of polarization to the photons in the static magnetic field. Other than that, I think your description is accurate.