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It is a light hearted joke that connecting a power strip to itself is a source of "infinite power". While this is obviously untrue, I always disregarded it and never really thought much of it, because I thought the reason was seemingly obvious. However, after actually thinking about it, I had a few doubts on what exactly would happen when you made such a connection.

My intial presumptions were that there would be no current because there was no source of emf, and such a connection would never cause a flow of charges becuase there will be no electric potential difference between the two pins of the socket. I think this is right, but please correct me if I am wrong.

On looking it up online, I found some sources suggest that the "remaining current" would "drain" away almost instantaneously. Other related terms were "charge stored in the wire" and "sapped by the resistance of the wire". This is causing a lot of confusion. All the terms in quotes are in my opinion, a poor choice of words and are really unclear to me.

The only close analogue I could come up with was an RC Circuit, that was discharging. This would justify the instantaneous draining of charge, and the build up of internal energy in the resistor (which I think are the meaning of those phrases). However, a discharging RC circuit in itself contains idealized wires and a parallel plate capacitor in series with a resistance. Imagining such a combination of elements in a single wire is actually confusing me a lot, and I cannot wrap my head around it.

If this is the correct analogy, could someone help me understand how a wire could act as a capacitor and a resistance simultaneously? If not, could you tell me how this instantaneous discharge occurs?

Any help would be appreciated!

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Forget about the details of circuit analysis for a moment and think of what the wire and plug is physically: it's a strip or rope of metal. Perhaps it is in several joined pieces (e.g. the "wire" part versus the "prong" part), and wrapped up with plastic insulation, but still. Hence, when you plug the wire into the power strip, it is no different from if you take a metal necklace and bring the two ends together to form it into a loop around your neck. You don't get a current here, so you won't get one in the power strip either.

And the reason in both cases why you don't get current is, as you point out, no emf: to get it, you need something to push the electrons in the wires so as to set them in motion, and to maintain such a current, at least in a resistive medium which all metals under everyday conditions are, you need to continuously supply that push. This means something like a battery or, in the case of a power strip being used in its intended fashion, the generator at a powerplant, must be in the system.

(P.S. in case you or whoever else is reading this doesn't already know or realize it, don't then put a battery into this configuration! The low resistance means it will draw a lot of current, will get very hot and the battery and/or wires will be damaged or worse, there will come forth great balls of fire! This is also called a "short circuit", of course.)

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  • $\begingroup$ Shorting a battery (i.e., connecting a wire between the battery's two terminals) is not the same "configuration" as plugging a power strip into itself (i.e., forming a loop of wire.) $\endgroup$ – Solomon Slow Jun 22 at 1:35
  • $\begingroup$ Thank you for the answer! Your answer is very clear on what I need to model the wire as ; a series of resistances that are not connected across an emf. However, could you please extend on what the "discharging" process is, in the wire, and how it happens so quickly? Thanks in advance! $\endgroup$ – Cross Jun 22 at 1:37

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