I'm very confused on this question. I've researched online but I can't seem to find the answer anywhere: all I was told was that electrons move (as part of electron flow) towards the regions of high potential away from the areas of low potential. What happens to the positively charged metal ions in the copper wire then? Do they just remain stationary and the electron movement makes up electricity? How would this look? What about the conventional current theory? Is it technically wrong because it claims positive current flows, or have I gotten concepts wrong? I have ab exam tomorrow and even though Im 14 and it wont be on my exam I still don't understand and its driving me insane. Please answer quick.
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1$\begingroup$ Atoms are localized in a lattice, whereas electrons can move. see this link to begin understanding hyperphysics.phy-astr.gsu.edu/hbase/electric/miccur.html $\endgroup$– anna vCommented Jun 23 at 18:58
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$\begingroup$ In certain constructions using semimetals the "current" is more easily represented as the movement of holes. See en.wikipedia.org/wiki/Charge_carrier . Also: for even H+ (protons) to move thru or along a conductive medium requires a lot more "push." $\endgroup$– Carl WitthoftCommented Jun 23 at 21:55
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4 Answers
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To answer this question, it is necessary to understand the structure of the metal at the atomic scale. A very simple way to see it is that the positively charged nuclei sit at fixed points in a crystal lattice, surrounded by a "gas" of electrons moving freely between them. Of course the real picture is more complicated, with some electrons being more strongly bound to the lattice than others, but this is irrelevant for now. What is relevant is that the electrons are the sole carriers of charge, while the positively charged remaining parts of the make up the physical structure of the wire. If they start moving as well, the wire loses its strucural integrity. This can actually happen if you send a high enough current through the wire: The flowing electrons still interact with the crystal lattice, and can impart enough kinetic energy onto it to even melt it.
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1$\begingroup$ I think an unmentioned part of Nadia's question is why positive ions moving in an electrolyte do not get absorbed by the electrode and move around in the metal the way electrons can and do. $\endgroup$ Commented Jun 23 at 19:10
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1$\begingroup$ 'the positively charged nuclei sit at fixed points in a crystal lattice, surrounded by a "gas" of electrons moving freely between them' Yes, but the question is why this is so. $\endgroup$– my2ctsCommented Jun 24 at 16:46
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The question is why the ions are localised and form a lattice, unlike the electrons. The reason is that they are typically 10000-100000 times heavier than electrons. Therefore they have very small, often negligible, kinetic energy. Unlike for the electrons they do not possess enough kinetic energy to pass close to one another.
A simple model of this behaviour is the Hubbard model. It describes localisation versus delocalisation in terms of two parameters: the hopping or kinetic parameter $t$ and the on-site repulsion $U$. For the ions $U \gg t$ so they are localised.
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It’s because the ions aren’t delocalized like the electrons are.
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In a zero resistance DC power line electrons keep on moving without accelerating, because there is no electric field inside the wire.
In a zero resistance DC power line ions keep on staying still without accelerating, because there is no electric field inside the wire.
In a zero resistance DC power line electrons accelerate, when the voltage is turned on.
In a zero resistance DC power line ions accelerate, when the voltage is turned on, but the pylons stop the ion lattice from moving quite quickly.
And now the case of non-zero resistance:
In a non-zero resistance DC power line electrons keep on moving without accelerating, because there is an electric field inside the wire, and resistance, the combined effect is zero.
In a non-zero resistance DC power line ions keep on staying still without accelerating, because there is an electric field inside the wire, and ions are resisting the motion of electrons. The combined effect is zero.
In a non-zero resistance DC power line electrons accelerate, when the voltage is turned on.
In a non-zero resistance DC power line ions accelerate, when the voltage is turned on, but the pylons stop the ion lattice from moving quite quickly.
