Timeline for Why does electricity need wires to flow?
Current License: CC BY-SA 3.0
15 events
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| Aug 12, 2013 at 20:02 | history | edited | dmckee --- ex-moderator kitten | CC BY-SA 3.0 |
Come a little closer to answering the question here.
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| Aug 12, 2013 at 18:32 | comment | added | fffred | I'd like to, but I don't know the answer! Thinking about it ... | |
| Aug 12, 2013 at 18:24 | comment | added | dfg | @fffred I think your the only person here who really understand what I'm trying to ask. Mind posting an answer? | |
| Aug 12, 2013 at 18:14 | comment | added | fffred | So it means that a good conductor cannot be used as an electrical wire if is has a low work function? Are there any examples of that? If you can, I would suggest to include in your answer an explanation of the work function rather than a difference of conductivity. | |
| Aug 12, 2013 at 18:10 | comment | added | dmckee --- ex-moderator kitten | @fffred Yes. But saying "work function" doesn't really explain it. Not that I've done a very good job of that. I suspect that my grasp of the solid state parts of this questions is shaky and idiosyncratic. | |
| Aug 12, 2013 at 18:07 | comment | added | fffred | Well, isn't that work function the reason why electrons won't get out of the metal? What happens in a metal with very low work function? Do the electrons freely get out of the wire and flow through air? | |
| Aug 12, 2013 at 18:00 | comment | added | dmckee --- ex-moderator kitten | The electrons are "free" in the metal which means that they are in the conduction band, but that is still bound to the bulk metal (the degree of binding is the work function that appears in an analysis of the photoelectric effect, BTW), and while they could get to lower energy by getting to the anode they are still facing a potential barrier at the surface of the metal. | |
| Aug 12, 2013 at 17:49 | comment | added | dfg | Electrostatic force of what pulls them back? the electrons are being pulled harder by the positive terminal than the negative terminal- that's what makes them want to move the in first place - so what would pull them back? | |
| Aug 12, 2013 at 17:46 | comment | added | dmckee --- ex-moderator kitten | As soon as they leave the terminal the electrostatic force pulls them back. That is not a problem in a wire because there are free electrons all along the path and in each path segment as soon as the local electrons leave their place is taken by those from the segment before just as they take the place of those in the next segment. If there is an ionized tracking leading from the cathode to the anode then current does flow through air for a short time: that is how leaf electroscope dosimeters work. | |
| Aug 12, 2013 at 17:27 | comment | added | dfg | In a galvanic cell, there are a bunch of free electrons at the negative terminal. Why can't the electrons move by themselves? Why do they need the electrons of the air particles? | |
| Aug 12, 2013 at 17:22 | history | edited | dmckee --- ex-moderator kitten | CC BY-SA 3.0 |
improve answer after comments
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| Aug 12, 2013 at 17:19 | comment | added | dmckee --- ex-moderator kitten | The electrons mostly are not lose to act as charge carriers in air. The field interacts with the whole (neutral) atom or molecule. Bulk metals have a "conduction band" which allows electrons to be free with much lower energy than in air. Drift chambers (a class of particle detectors) work by moving electrons through gas, but they require that the atoms are ionized first (and use high fields because the electrons will recombine in fairly short order). | |
| Aug 12, 2013 at 17:18 | comment | added | dfg | I guess what I'm really asking is if a ball can move through the air, why can't an electron? | |
| Aug 12, 2013 at 17:15 | comment | added | dfg | But aren't the electrons the charge carriers? Why can't they carry the charge through air? (even though it would be extremely slow). In other words why can't the electrons move through the air like a ball would? | |
| Aug 12, 2013 at 17:13 | history | answered | dmckee --- ex-moderator kitten | CC BY-SA 3.0 |