In a Leyden jar, I have read that a charged object is brought in contact with the conductor in contact with the metal inside the jar, thus giving the inner metal a similar charge. And the metal outside the jar then gets an opposite charge.

My question is simply how does the metal outside the jar get the opposite charge, given that there is an insulator in-between?

I hope that someone can give me a clear reply, explaining exactly what happens with the outer metal.


The inner conductor is charged through conduction of charge and the outer through induction.

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  • $\begingroup$ "The outer through induction." Thank you. Can you please expand on that in a bit of detail? $\endgroup$ – oyvey May 16 '14 at 15:09
  • $\begingroup$ The outer foil does not need to have any net charge, as long as the inner foil is relatively charged. If the charge on the inner foil is strong enough, it will repel the negative charges into the surrounding material, thereby inducing a charge. The important aspect of such a device (capacitors in general) is the difference in charge divided by the voltage. The outer foil can be grounded and the capacitor will still function. $\endgroup$ – KidElephant Jul 18 '14 at 15:17

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