1
$\begingroup$

I am trying to understand how electricity works on quantum level. Precisely how is energy actually transferred from generator to the consumer.

Here is what I managed to understand so far by reading Wikipedia and some articles online:

Electrons inside the conductor have gravitational like forces of attraction to protons and repulsion to each other. The electromagnetic field created by the generator moves the closest electrons inside the conductor, they in turn move closer to the other electrons which forces those electrons to move away and thus a chain reaction starts in the entire length of the conductor. As all these electron move through the wire they create an electromagnetic field which is directional along the conductor from the generator to the consumer. The waves of this electromagnetic field carry the electric energy.

Each stationary electron has an electric field around it. As the electron moves it also creates a magnetic field. Both of these fields combine into electromagnetic field which propagates in a wave like pattern in all directions. Sort of like a pulsating sphere? Since all these electrons are constantly on the move in random directions their collective EM field summarized as an uniform field around the object with waves emanating away from the object. As soon as electrons start to move in one direction the EM field waves start moving in the same direction as the electrons.

The EM field consists of individual photons traveling from one electron to another. If a photon bumps into an electron it gives momentum and electron loses its orbit and starts to move. If a moving electron (e1) comes close to another electron (e2) the first one (e1) is stopped by the repulsion force and its photons escape to the second electron (e2) witch in turn also obtains momentum and starts to move. If a moving electron is caught by a proton and settled on an orbit it photons escape in random directions creating light and heat (resistance). At the same time some photons also travel on the outside of the electrons in a uniform direction as a part of the EM field in a wave like pulse.

I think my understanding above is wrong in some way. I would appreciate if you could point out my mistakes and give advise as to what I could read to get a clearer picture. Preferably something simplistic without math formulas.

Thank you!

$\endgroup$

1 Answer 1

2
$\begingroup$

One big problem with the description that you gave is that it relies on photons, which may be useful for understanding electromagnetic waves and very high-frequency circuits, but they are useless for understanding a simple direct current circuit. (The photons at DC would have no energy).

To get a good understanding of energy transfer in simple DC circuits it is best to completely avoid the concepts of electrons and photons entirely. Those are fundamentally quantum mechanical concepts, and until you are ready to dive into the deep mathematics of quantum mechanics you will not be able to treat them as they actually are, but instead just work with a cartoonish misunderstanding of them.

So, classically the key to understanding energy transfer in electrical circuits is the Poynting vector and Poynting's theorem. This says that energy flows in a direction that is perpendicular to both the E field and the B field as given by $\vec S = \frac{1}{\mu_0} \vec E \times \vec B$. This is shown for a simple circuit in the following image: Poynting vectors of DC circuit

Note that energy flows through the fields, and is actually transported to the load outside of the wires. Inside the wire, the E field is along the wire and the B field is circumferential. So by Poynting's theorem, inside the wire the energy is actually transported radially inward i.e. the resistive losses in the wires. The energy that goes to the load does so outside the wire.

$\endgroup$
5
  • $\begingroup$ On a transmission line of two parallel wires the E field is pointing from one wire to the other, that is in between them and not along; thus the Poynting vector $S=E\times H$ is along the wires. $\endgroup$
    – hyportnex
    Commented Aug 24, 2021 at 18:23
  • $\begingroup$ @hyportnex yes, exactly. And if you look at the magnitude of the Poynting vector (not depicted in the image) you find that most of the energy travels outside but very close to the wires. $\endgroup$
    – Dale
    Commented Aug 24, 2021 at 18:44
  • $\begingroup$ I know you know but the way you have phrased may appear a bit convoluted to a novice, methinks $\endgroup$
    – hyportnex
    Commented Aug 24, 2021 at 19:00
  • $\begingroup$ Your explanation describes what is happening. That energy is transferred from the source to the consumer via the EM field. But my question is why is this happening the way it does, and how exactly on the quantum level. $\endgroup$
    – Orange
    Commented Aug 25, 2021 at 7:01
  • $\begingroup$ @Orange as I said, the quantum level is useless at DC. There are no EM waves, no wave like patterns, and the “photons” have no energy. $\endgroup$
    – Dale
    Commented Aug 25, 2021 at 10:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.