lol, sorry, when I said EM I meant the Coil that created the Magnetic field.

 

here is how it should be read:

I sorta of think of the magnetic field as separate from the Coil and the field as it spreads out over time energizes space, in this space are Virtual Particles that pop in and out and the closer to the source the more dense the Virtual particles are so the more energy. This explains the field spreading out and causing detectable effect's at some distant object if sensitive enough. When the field collapses, it does not really collapse but instead the Coil stops Creating the field and so as it stops energizing space and so the Virtual particles that were created fall back to the vacuum and in doing so create a field that again spreads out but this time it spreads out back toward the Coil and as more and more Virtual particle collapse back to the vacuum, the field becomes just as strong as it was when Coil was on. This effect now creates the back-EMF. It is more complicated then that but for me that effectively describes what happens in both cases.

Now for the question on why do different resistor values change how fast and slow the Coil Discharges and Charges, well that is all because of the circuit, the Field (magnetic field) collapsing back never collapses back faster or slower, it collapses back and at the same speed as it spread out, so as you can see it is the circuit parameters that determine fall times and rise times.

 

You refer to virtual particles. What the heck are you talking about? What particles? To me this is a nonsense term.

The instantaneous current determines the size of the magnetic field. I do not quibble with the speed a magnetic field propagates, but how fast it grows or shrinks is a direct consequence how the current is shifting, which is dictated by the RL charge curve.

 

As long as current is flowing in the coil a field will persist. If you increase the resistance in series with the coil, the field will persist for longer. The energy that 'powers' this is in the field.

BTW, the LR time only works if there is only one coil in the field. Another coil in the field with a load on it (AKA transformer) will change this as there is another sink for energy in the field.

 

Perhaps, but why are you over complicating the issue? One coil is enough for now.

Just as a cap wants to maintain a voltage, a coil wants to maintain a current. Remove or change the source current, and the magnetic field collapses inward, generating an EMF that will attempt to maintain the current. If the circuit is completely open the EMF will be a very high voltage.

The magnetic field collapsing inward (ie, moving) is what generates the voltage.

 

You refer to virtual particles. What the heck are you talking about? What particles?

QED uses virtual particles (actually photons) to mediate the repelling force between like charges. Emitting a virtual particle causes a reaction, and capturing the particle causes another.

QED holds that an electric charge causes a cloud of virtual photons to come into existence and surround it. It may seem as is energy is being created, but the uncertainty principle holds that a determination of energy and time can't be done simultaneously, so it is impossible to say if energy is being conserved.

A demo of the reality of virtual photons can be made by removing the charge that causes them to exist. Like you accelerate an electron and crash it into metal. The virtual photons turn up as X-rays.

Too bad the evidence to demonstrate gluons and gravitons is more than a bit thin. Quantum electrodynamics is kinda shaky there.

This does not have diddly to do with magnetic fields and induction.

 

actually it does have to do with magnetic fields and induction, well from what I know. The Virtual photon in QED is the Force carrier for not only the Electric charges but also the Magnetic field. If I am wrong, then please tell me and why and what is really the force carrier for the Magnetic field.

For induction the reason it is important is because in say a conductor, there are electrons and these electron inherently have a their own magnetic field due to their spin, and orbit or movement. As the you apply a voltage, these electrons move around the conductor setting up the magnetic field around it. When you try to shut off the Conductor, the initial field starts to collapse, if the field is made of energy and the virtual photons are the force carrier, then I would assume the field and the virtual photons are in someway intertwined. As the field collapses, the field will start to cause a force (Virtual Photons) on the electrons, causing them to want to keep moving in there original direction, if you just cut the circuit, this will cause a huge increase in voltage because of the charge buildup at one end due to the field acting on the electrons (virtual photons). Even though there is no connection at this point, the collapsing field still causes a force on the electron's and this force is caused according to QED from the virtual photons.

So that is why according to what I know, the virtual photons have a lot to do with Magnetic fields and induction, I just haven't found out why a steady state field doesn't induce and a changing does?

 

Kermit2 appears to feel they are somehow 'fixed' to the source, so that if you rotate the source, the lines, and hence the field will rotate.

It would appear a wrong interpretation of my previous post was made. I was asking in a rhetorical way, why the generator behaved in those ways. I did intend for a reader who held these assumptions to question them and, if not do the experiment himself(rarely happens anymore), to go to the web and search for information on why/how magnetic fields could remain stationary while a magnet rotated.

Should I edit my previous response? I looked at it again, and I don't interpret the way you did, but I wrote it, and I'm not you, so.....

 

actually it does have to do with magnetic fields and induction, well from what I know. The Virtual photon in QED is the Force carrier for not only the Electric charges but also the Magnetic field. If I am wrong, then please tell me and why and what is really the force carrier for the Magnetic field.

For induction the reason it is important is because in say a conductor, there are electrons and these electron inherently have a their own magnetic field due to their spin, and orbit or movement. As the you apply a voltage, these electrons move around the conductor setting up the magnetic field around it. When you try to shut off the Conductor, the initial field starts to collapse, if the field is made of energy and the virtual photons are the force carrier, then I would assume the field and the virtual photons are in someway intertwined. As the field collapses, the field will start to cause a force (Virtual Photons) on the electrons, causing them to want to keep moving in there original direction, if you just cut the circuit, this will cause a huge increase in voltage because of the charge buildup at one end due to the field acting on the electrons (virtual photons). Even though there is no connection at this point, the collapsing field still causes a force on the electron's and this force is caused according to QED from the virtual photons.

So that is why according to what I know, the virtual photons have a lot to do with Magnetic fields and induction, I just haven't found out why a steady state field doesn't induce and a changing does?

I asked you first. You state there is a particle, then name it. A permanent magnetic field (according to latest theory as I understand it) is caused by the spin of an electron. If enough electrons are oriented the same way the field becomes noticeable. If not they they all cancel. An electromagnet does it differently, but it still depends on electrons, the circular winding of a coil concentrates the field which is always present in a wire conducting electricity.

You are making assumptions, and presenting them as facts. Not good for understanding anything. Following your logic there needs to be a carrier for an electric field, which is the inverse of a magnetic field. Far as I know there isn't, and I wouldn't assume there was.

You still cling to the assumption that a static field is moving when it is not. Near as I can tell this is the heart of your lack of understanding.

 

why/how magnetic fields could remain stationary while a magnet rotated.

It is comments like this which formulated my interpretation. Let me ask, what makes you ponder this? Give me a guess as to why you think a magnectic field would roatate with its source?

Let me see if I can explain how I think of fields. If such a field had a confined variance located radially away from the rotational axis of the source magnet, I would see this variance rotate through the field around the axis when the source rotates, but not the field itself.

Here is another example. Take the field I described above. The one with the small variance off to one side. Now, add another source fixed to a different mount that will not rotate. Imagine this new source adds several more localized variations to the field. We have now a different field, but one field nonetheless. Now as we rotate the first source, we see that it's variance does indeed rotate through the field, but the variances produced by the second source do not.

I have never thought of a field as having any kind of 'rigid' or 'mechanical' structure. It is not 'anchored' to any frame of reference.

Should I edit my previous response? I looked at it again, and I don't interpret the way you did, but I wrote it, and I'm not you, so.....

Not as far as I'm concerned. It's your post though, so you can do this if you wish.

 

In a fieldless vacuum, it may spin.

But on Earth, the field will stay put in relation to the Earths magnetic field.

If you have a horseshoe magnet and spin it, the field moves with the magnet.

It could be that with a cylindrical shaped magnet the field is spherically equal so it DOES move, per se, but the effect at any one point stays the same.

Without a changing VALUE, no voltage is induced. So the field COULD move, but if the strength does not change, it appears still.

 

Bill_Marsden, I think you are correct, saying that "You still cling to the assumption that a static field is moving when it is not. Near as I can tell this is the heart of your lack of understanding"

But I guess one of the big reasons for seeing the Magnetic field as composed of virtual photons or at least in some way part of, is because according to QED, the force carrier is the Virtual photon. Also yes the electron or more precisely the charged particle is where the magnetic field originates. All QED says though is that the field is in reality composed of these Virtual Photons and these are what are responsible for all the interactions involving the magnetic field, even between something macroscopic like two coils.

about your statement " Following your logic there needs to be a carrier for an electric field, which is the inverse of a magnetic field." The carrier or as far as forces are concerned, there is and it is the virtual photon, I know weird but that is what QED says?

So I guess my problem is either not understanding QED, lol (more then likely) or Trying to combine two different views that just aren't easily combined, lol (also more then likely)

 

Originally Posted by Kermit2
why/how magnetic fields could remain stationary while a magnet rotated.

It is comments like this which formulated my interpretation. Let me ask, what makes you ponder this? Give me a guess as to why you think a magnectic field would roatate with its source?

I'm typing, but your eyes are deaf or something.

I started to write some rebuttal to correct your mis-interpretation of my beliefs and why you don't need to 'teach' me anything, but YOU are waste of my time at this point.

Good day. And I hope you get the 'interpretation' of this post right where I aimed it.

 

This thread has generated some disagreement, and some heat. Most seems to come from the nature of a magnetic field:

Kermit2 appears to feel they are somehow 'fixed' to the source, so that if you rotate the source, the lines, and hence the field will rotate

There is an experiment that appears to shed some light on this. I have a couple of magnets stuck to my drill press to hold pilot drills and some common sizes in easy reach. The drills are themselves magnetized, making classic bar magnets.

A few seconds with a grinding wheel and a soft bolt produces iron (mild steel) filings. On a sheet of paper, they arrange themselves as expected when a magnetized drill is held against the back of the sheet. That is the classic demonstration of field lines. Rotate the drill in the plane of the paper and the filings follow.

It is interesting to note that the drill may be held against the paper so that only the blunt end is in contact. The filings respond in the expected manner. They also show rotation when the drill is slowly spun.

Is this showing a fixed field rotating with its source, or does some other explanation apply?

 

Originally Posted by Kermit2
why/how magnetic fields could remain stationary while a magnet rotated.



I'm typing, but your eyes are deaf or something.

I started to write some rebuttal to correct your mis-interpretation of my beliefs and why you don't need to 'teach' me anything, but YOU are waste of my time at this point.

Good day. And I hope you get the 'interpretation' of this post right where I aimed it.

Well, thanks for the insult. I'll try not to do the same.

 

Is this showing a fixed field rotating with its source, or does some other explanation apply?

My guess is that the field produced by the tool is hardly uniform.

But I'll stop trying to convince anyone at this point.

 

Proof by assertion?

Taking a magnet, we note a magnet field is bound in some way to said magnet. If the field moves in every other way with the magnet, how is it unable to rotate with the magnet?

Perhaps you could set forth some conditions so we are all on the same page? Most importantly, "rotation".

 

This is a pretty aggressive site. No, I am not saying proof by assertion.

I am saying I no longer wish to prove anything. You can believe whatever you like.

Okay, I'll try to give another thought experiment on this, but this is for demonstration purposes, not proof.

Think of a long, uniform, ideal, cylindrical magnet. Longer than it’s diameter, just to make things clear. Now, imagine that the poles are opposite ends of the cylinder. Now rotate the magnet around the cylindrical axis. Does the field rotate?

Now imagine you have two such magnets. Place them coaxially end to end, north pole of one the south pole of the other and separated by a fixed distance. Can we assume there is a field between them? If not, slide a slim coil attached to a suitable meter between them and jiggle it about to satisfy yourself that there is a field there. Now, rotate one of the magnets around its cylindrical axis. Does the field between them rotate? Or perhaps it gets all twisted up?

 

you guy's are confusing me with the different ways your describing things, how about every one pick there ideas from the pages on this site; http://www.physics.sjsu.edu/becker/physics51/induction.htm So every one can be on the same page in there theory.

 

Thanks shortbus, all the basic stuff is there. I'd bet most of us here are familiar with this level.

However, can you quantitatively define a 'magnetic field line' for us? They are used rather extensively in the explanations at that site, but they are not defined.

How do we measure, or count, the number of them going through any particular loop at any particular time?

In the diagrams at that site, the field lines are shown firmly embedded in the sources of the fields. Is this the case? If we rotate the source about the axis at the center of the field lines, do they rotate with it? Does a particular discrete field line always emanate from the very same spot on the surface of the source? What is it about that spot that warrants a field line? Why is that spot so unique? What is the exact diametric extent of the field line, or, how thick are they? What lies between them?