Comment by marshray
10 years ago
These are two great responses, but they seem to be saying opposite things.
https://news.ycombinator.com/item?id=10877121
One says electrons bump into electrons, the other says electrons bump into non-charge-carriers. Someone on Twitter said it was phonons.
I guess I can kind of imagine a pachinko machine, but this is all very unsatisfying. :-)
Edit: From the Wikipedia link: "Charged particles in an electric circuit are accelerated by an electric field but give up some of their kinetic energy each time they collide with an ion"
I mean, electrons are very very lightweight and tend to move quite slowly for typical currents. How much kinetic energy can they give?
> "I mean, electrons are very very lightweight and tend to move quite slowly for typical currents. How much kinetic energy can they give?"
I only have a layman's understanding of this whole process, so I could be missing some important details, but I believe it's necessary to look at the atoms as a whole rather than just the electrons...
Consider, the electrons (from the outermost orbit of the nucleus) are travelling from atom to atom (the ease by which they can come and go determines how conductive the material is).
During this process, when an atom has more electrons than its stable state it is negatively charged, and when it has less electrons than its stable state it is positively charged. The greater the polarisation between the positively-charged atoms and the negatively-charged atoms, the more electrons can move through the material. I believe the potential difference between the poles is voltage, and the volume of electrons flowing at a given time is current, but I could be wrong on that.
Electrons lose their energy to other things.
Here's one quick explanation why:
If electrons lost their momentum and energy only to other electrons, then in aggregate, electrons would keep their momentum and energy. Since electrons do not permanently keep their momentum and energy in normal conductors, they therefore must lose momentum and energy to non-electrons.
Also, if you look at the Wikipedia link on the comment that says claims electrons lose energy to electrons, you'll see that Wikipedia says electrons lose energy to ions, not electrons.
(Also, as a condensed matter physicist, I always feel a little dirty/inaccurate saying that electrons carry charge currents. I prefer the vaguer charge carrier, because charge carrier can refer to an ensemble of electrons.)