Why Does Current Flow When a Capacitor Is Connected by Wires?

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SUMMARY

The discussion centers on the phenomenon of current flow when a charged capacitor is connected via wires. It is established that while electric fields outside a charged capacitor may cancel due to superposition, the leads of the capacitor can still exhibit a voltage difference, resulting in current flow. The construction of capacitors, which includes layers of metal and dielectric, contributes to the presence of an electric field around the capacitor's plates. This understanding is crucial for recognizing the dangers associated with charged capacitors, particularly in high-voltage applications like microwave ovens.

PREREQUISITES
  • Understanding of capacitor construction and operation
  • Knowledge of electric fields and voltage concepts
  • Familiarity with superposition principle in electromagnetism
  • Awareness of safety precautions around high-voltage devices
NEXT STEPS
  • Research the principles of electric fields around capacitors
  • Study the superposition principle in electromagnetism
  • Learn about the construction and applications of capacitors in high-voltage devices
  • Explore safety measures for handling charged capacitors in electronics
USEFUL FOR

Electronics engineers, physics students, and anyone involved in the design or maintenance of electrical systems, especially those working with capacitors and high-voltage equipment.

unseensoul
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There are no electric fields outside of a charged capacitor as they are canceled out due to superposition, right?! So why is there a flow of current when a cable is connected to both ends of the capacitor?

I was told that there might be an E field in the wires. How come? Where does it come from?
 
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A charged capacitor can be discharged by connecting the plates together.
That is what you do when you connect the two ends of a charged capacitor by a piece of wire.

A capacitor is made by making layers of metal and dielectric in a spiral on a central rod.
This means that one of the layers of metal must be on the outside of the capacitor. ie they can't both be on top.
So, this plate of the capacitor would certainly have a field around it if the capacitor was charged.
Maybe your first assertion isn't correct for normal capacitors?

Not sure what you mean by an "E" field. The leads of a capacitor can certainly have a voltage between them. There is a capacitor in all microwave ovens that is very capable of killing you.
 

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