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Suppose when we connect one wire with current conducting wire then it also becomes negatively charge which has potential to accept electrons. But when we break the circuit, the wire becomes neutral again and doesn't have potential to conduct current. How at one time it is negatively charge but when we break the circuit then suddenly it becomes neutral ?

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  • \$\begingroup\$ can u draw us a picture.... \$\endgroup\$ – Trevor_G Mar 19 '17 at 16:21
  • \$\begingroup\$ The full answer to this question, dealing with transmission line effects in wires, is kind of complicated. But under normal circumstances, the wire is not actually charged. The electric potential comes from the source. The number of electrons in the wire is the same, before during and after you connect and disconnect it from the voltage source. \$\endgroup\$ – mkeith Mar 19 '17 at 16:32
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Actually, it does retain a charge. But that charge is tiny, and it drains away as soon as you connect a voltmeter to measure it. You need to use an instrument like an electroscope, which has essentially infinite input impedance.

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  • \$\begingroup\$ (Upvote because you were 32 seconds faster. :-) \$\endgroup\$ – skvery Mar 19 '17 at 16:31
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    \$\begingroup\$ Assuming u disconnected both ends... \$\endgroup\$ – Trevor_G Mar 19 '17 at 16:36
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The wire remains charged. The wire has capacitance, but this is very small.

If you make the wire long enough or the voltage high enough, you will be able to detect it.

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You've asked a question better suited for the physics forum, but I think the general answer to your question is that the wire never has an unbalanced charge. The electrons in it are being subjected to an electric field, causing them to move. The charge imbalance is in the power supply.

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  • \$\begingroup\$ Better to say that there is no charge imbalance. Everywhere in the whole entire circuit, KCL applies. Any electron that flows into a node is balanced by another one flowing out, so that the net flow is zero. \$\endgroup\$ – mkeith Mar 19 '17 at 16:34
  • \$\begingroup\$ @mkeith: Actually, that's an approximation that we use in order to simplify lumped-value circuit analysis. In reality, any circuit node that has nonzero dimensions has some amount of capacitance to the world at large and can retain a charge. \$\endgroup\$ – Dave Tweed Mar 19 '17 at 16:42
  • \$\begingroup\$ @DaveTweed, yeah. It is a little bit of a judgement call on the best way to present this to a beginner. KCL is very important, and relies on the idea that circuit elements do not accumulate charge. In this specific answer, I am merely objecting to the idea that there is a charge imbalance in the battery or power supply. I believe that is misleading to the OP. I think your answer is good. \$\endgroup\$ – mkeith Mar 19 '17 at 16:47

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