what happens to electrons in a cut wire.
I know it is dangerous but out of curiosity if there was a power cable cut and connected to the outlet, the electrons would be dispersed in the air when they reached the cut edge of the cable?
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$\begingroup$ If there is a path that could lead to a transfer of electrons and the voltage is high enough, then the air (assuming the wire is in air) would be able to conduct electricity (Look up dielectric breakdown) and we can observe this effect - youtube.com/watch?v=og-BHYy-fhI&ab_channel=Eventhorizon2112 I wonder what would happen if these conditions aren't met. What would the electrons do then.. $\endgroup$– MitchellCommented Dec 26, 2020 at 2:21
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2 Answers
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As the comment by @Mitchell already points out, dieletric breakdown is something that could happen. If the wire is at high enough voltage, then it may ionise the air to reach the ground, which would be the low voltage terminal. This is what happens with lightnings.
The voltage required for the above is usually in the thousands of Volts, which is unusual to find in a common mains cable.
The danger then is if you touch it. Then, your body is essentially a second "wire" that connects that cable to the ground. Power cables may reach up to 415 V for three-phase sockets in Europe. If you are not wearing shoes and your skin in wet, your body would have quite a low resistance, enough for a sizeable current to flow through you. Which can cause a number of problems: stop your heart (fibrillation) or burn you. All in all, not ideal.
This is especially dangerous if the cables come directly from the wall, that is not after a DC power supply like your phone or laptop charger. Those DC voltages are usually <24 V which are innocuous.
answered Dec 26, 2020 at 2:29
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$\begingroup$ "But if the wires come from the wall, then it's an AC voltage, so both the live and the "neutral" wires reach high voltages." – Are you sure about that? The neutral wire is connected to ground somewhere, so under normal circumstances, it should never carry a high voltage relative to ground. (Of course, under abnormal circumstances, it could very well carry a high voltage.) $\endgroup$ Commented Dec 26, 2020 at 5:22
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$\begingroup$ In the EU for example, wall sockets have three wires: live, neutral, and earth. The live and the neutral and the + and - terminals, sure, but the voltage is AC so they both oscillate. This is why, in electronics boxes that connect to the wall, switches are DPDT that open the connection on both the live and the neutral ones, whereas for a DC power supply you just need to open the connection to the high voltage one).This also extends to the three phase sockets that I used as an example because of the higher voltage. $\endgroup$ Commented Dec 26, 2020 at 5:25
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$\begingroup$ The earth wire is connected to (the) ground somewhere. $\endgroup$ Commented Dec 26, 2020 at 5:25
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$\begingroup$ "The earth wire is connected to (the) ground somewhere." – Yes, it is, and, in my experience, the neutral wire is always connected to the earth wire somewhere. This causes the neutral wire to be at a low voltage relative to the earth wire all of the time (unless something is broken). If the resistance of the neutral wire is 0.2 ohms, and the RMS current through it is 10 amps, then the RMS voltage on the neutral wire is going to be just 2 volts, regardless of what the voltage of the hot wire is. $\endgroup$ Commented Dec 26, 2020 at 5:44
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$\begingroup$ In AC circuits the neutral and live wires are identical. Just out of phase. They both carry high voltage. It's as if they were the +15 and -15 V power connections to an op-amp. The earth 'ground' would be at 0. $\endgroup$ Commented Dec 26, 2020 at 5:45
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You can basically think of any waves (signals, AC power, etc) as being nearly perfectly reflected at the new termination point. This can give rise to standing waves and stop all net flow. So, if you cut the cable and leave it there on the ground, nothing will flow out. If you touch it, you're now part of the cable and probably regretting it.
