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If a positive plate of a capacitor is connected with its negative plate using a zero resistance wire, both having the same amount of charge but with opposite signs, do the plates get neutral after some time? Or do the charges oscillate? It's hard for me to imagine. Please explain by comparing the zero resistance case and the regular wire case.

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3 Answers 3

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If you have a zero resistance you still have inductivity, there will be am magnetic field, when it collapses, the capacitor is recharged in the opposite direction and so on. (depending of the arrangement of the wire part of the energy goes into an EM wave) If you have resistance part of the energy $C/2U^2$ is converted to thermal energy in every cycle, if resistance is high enough there will be only one half cycle.

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  • $\begingroup$ Is there a youtube video which explains this, capacitor and a zero resistance wire connected. $\endgroup$ Oct 3, 2021 at 3:16
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The system: charged capacitor + wire is electric equivalent to a mass spring system. The system will oscillate.

In the case of a wire with a small resistance, the oscillations will fade gradually, until the neutrality of charges be reached. If the resistance is big enough, there is no oscillations, and the charges tend exponentially to neutrality.

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The capacitor will discharge instantly if wires have 0 resistance.

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    $\begingroup$ You are forgetting the mass of the electrons. This leads to a form of inductance called kinetic inductance that means the circuit is effectively an LC oscillator. $\endgroup$ Oct 2, 2021 at 14:39
  • $\begingroup$ I'm guessing that the magnetic fields associated with current flow through the wires and plates would be a more significant source of inductance than the mass of the electrons. $\endgroup$
    – R.W. Bird
    Oct 2, 2021 at 15:12
  • $\begingroup$ I answered the OP's question according to what I know. Discharging of a capacitor through a resistance and as the resistance tends to 0 current tends to infinity so the capacitor should discharge instantly , being honest I had never heard of kinetic inductance thanks for the information. $\endgroup$
    – Steve
    Oct 2, 2021 at 18:00

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