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Question: Does electric energy propagate as electromagnetic waves and if that is the case, how? This is clearly not the same as propagating EM waves by an antenna whatsoever. If that was the case we wouldn't be filling the world with wires.

Some details about what I know about our electrical system below.

In AC power lines, electrons oscillate back and forth for miles and miles, if I understand this right the electrons move in the direction of electric field and the two are in sync. If this be the case then there must be electric field outside the wires and on the surface of the wire. The magnetic fields change direction orthogonally to the direction of the current and electric field and is also on the wire.

If I have that right, are there electromagnetic waves propagating from the wires every which way? Or is it linear, and if so which direction? Three-phase wires have certain distance from each other and typical home wirings are close to each other in one insulated solid configuration.

If this wave does exist, and the wires go on for miles, I just can't picture how this oscillation maybe and the result of EM waves. Is it at each point on the wire, knowing that the waves are ultra low frequency? Something does not add up in my head.

Also, the Poynting vector, being a cross product of the magnetic and electric field, does this mean that energy enters the conductors from outside the wires into the current carrying wires at all points inward orthogonal?

Furthermore, at the source of power generation, I assume EM waves exist with its own direction moving away in certain direction. Does it result in Poynting vector pointing outward at the source? (I am interpreting Poynting vector as being the energy density and its direction and that it is neither in the direction of electric or magnetic field nor is it in the direction of EM propagation, nor in the direction of current. That seem to cover all 3 dimensions. It doesn't sound right as there is no 4th dimension)

(Furthermore I am interpreting that most of the EM field is not far field but near-field and also not considering any back ward propagation towards the source due to all the other capacitance and inductive loads) And I assume that in essence it is pretty complicated phenomenon.

Energy entering the wires at all points, is the most difficult for me to picture if that is the case. At the source I assume EM waves leave into the empty space as is energy density flux Poynting vector, they point away leaving the source into empty space, and the same for the load; energy flux pointing out leaving the load.

And the energy that enters the wires may not necessarily be the same energy the leaves the source and the same with the energy that leaves the load. To my understanding, they don't have to be the same energy. So how on earth does the communication takes place?

And at last, how does the energy propagate from the source to the load if not in some way by means of EM propagation? The energy certainly moves far faster than the electrons vibrating back and forth and in one direction too from the source to the load.

On another note, I do not have the slightest idea how energy moves in DC circuit. My question comes from the understanding that energy is delivered by means of photons/electromagnetic waves when it comes to currents, electricity phenomenon.

There is something I am surely missing. I can only think that this energy moving from the source to the load is not in the form of radiation or propagation which can not be in the direction of current either.

I hope I made some sense and my question is clear at least somewhat. Most likely, I will be asked to edit. It will end up the same long narrative, and will end up pieced together bit by bit deffered instead of all in one place.

Thank you in advance.

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    $\begingroup$ Hi, please avoid asking too many questions in one post. This needs to be edited down to one clear question. $\endgroup$ Jul 23, 2021 at 3:56
  • $\begingroup$ Vincent Thacker, There is just one question obviously, isn't it? How does the energy propagate from the source to the load. Most of everything else in the post is to stop generic seeming answers. And that is also obvious. So whoever answers the question knows that I am aware to dismiss seeming answers. Unless of course the person answering the question , if I get lucky shows one or many issues to be false and give the correct version to support his/her answer. Anyone answering will have to cross those points or simply not read it and that will show. $\endgroup$
    – user232620
    Jul 23, 2021 at 5:51
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    $\begingroup$ If you are willing to view the AC power line as an antenna then see p. 710 in this paper. $\endgroup$
    – Kurt G.
    Jul 23, 2021 at 7:43
  • $\begingroup$ No, I understand how an antenna work or how you can even light up a bulb in its proximity. My question is not about antenna at all. I simply want to know how energy is propagated in electrical system that we use. You can't exactly run your motor by an antenna although that may have been the goal of Tesla, to send electric energy wirelessly without too much loss. Electricity are charges and electric energy is something totally different I think. And I would think that this energy is transferred by EM waves. So how this wave interact with respect to conductors? $\endgroup$
    – user232620
    Jul 23, 2021 at 19:48
  • $\begingroup$ The Big Misconception about Electricity video led me here; some might find it and the animation enlightening (I missing too much of the basics yet) $\endgroup$
    – toraritte
    Mar 19, 2022 at 10:24

2 Answers 2

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Does electric energy propagate as electromagnetic waves and if that is the case, how? This is clearly not the same as propagating em waves by an antenna whatsoever.

Yes, it does propagate as electromagnetic waves, but it is what is known as the near field. This means that the energy propagates in the fields outside the wire (rather than in the wire), but the energy stays localized near the wire and does not radiate far away.

In AC power lines, electrons oscillate back and forth for miles and miles,

The electrons often oscillate less than 1 mm. In very high currents maybe 1 cm. To get an electron to oscillate a mile would require currents so high that it would instantly vaporize the wire.

I think you are thinking of the fields, which do have a long wavelength.

If I have that right, are there electromagnetic waves propagating from the wires every which way?

Yes, there are far field waves, but they carry very little energy.

Also, the Poynting vector, being a cross product of the magnetic and electric field, does this mean that energy enters the conductors from outside the wires into the current carrying wires at all points inward orthogonal?

No, you have the orientation wrong. There is a surface charge on the wire which makes the E field outside the wire point radially outward. The current in the wire produces a B field outside the wire which is circumferential. The cross product outside the wire is therefore along the wire. This is the energy that is transported to the load.

Inside the wire the E field points along the wire, while the B field remains circumferential. The cross product inside the wire is therefore radially inward. This is the energy that is lost to resistive heating in the wire itself.

The Poynting vector points out from the source and in towards the load. The overall energy flow looks something like this:

enter image description here

I do not have the slightest idea how energy moves in DC circuit.

The principles are the same as above, except that there is no far field.

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You have too many questions in one post. I'll answer the first one that comes up.

Question: Does electric energy propagate as electromagnetic waves and if that is the case, how?

Electrical energy is the energy output from an electrical potential difference. To do this, you have to separate charges at the beginning. After the separation, the potential difference (separated charges) can be connected by a wire and an electric current flows.

The electric fields of the negative and the positive charges, be they separated or not, always exist. At one time they are enclosed in the atoms, at another time we separate them artfully in electric potentials.

*Electromagnetic waves are obtained when charges (electrons) on the surface of a conductor are accelerated back and forth by a potential difference. While the oscillating electric field points along the conductor rod, the resulting common magnetic field of the charges is directed around the conductor cross-section. Since the electrons are all accelerated together, the resulting EM wave is polarised and an oscillating electric current is again generated at the surface of the receiving conductor.

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  • $\begingroup$ Holgerfiedler, What this has to do with the question? It is obvious there is just one question, where and how does the energy flow from the source to the load in elecricity via power line? Well, I guess I can't get a straight foreward answer as usual. So I have to answer it my way. $\endgroup$
    – user232620
    Jul 26, 2021 at 18:08

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