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I am studying Capacitance for my Physics class. We have been working with parallel-plate capacitors, which I understand perfectly. However, I’ve seen some exercises with spherical and cylindrical capacitors. In them, I have learned to calculate the capacitance by simply applying the definition, but I am having trouble deriving the maximum potential difference and maximum potential energy that can be present before dielectric breakdown. Can you please explain this to me? I really want to understand these concepts, as I do for the parallel-plate capacitor.

All help greatly appreciated!

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At which surface is the electric field (potential gradient) the largest?

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That is where electrical breakdown is most likely to happen.

From that you can find the potential at that surface and hence the required potential difference.

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  • $\begingroup$ It’s at the surface of the inner sphere, right? So then I can use the definition of capacitance (having calculated the maximum charge from the field) to get the maximum potential? $\endgroup$
    – Bee
    Commented Oct 29, 2017 at 20:24

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