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I want to ask a question about capacitors in parallel.

I was presented with the following question, and I want to show you my attempt to the question.

A 20μF capacitor is charged to 9.0V, then disconnected from the supply and then connected across an uncharged 10μF capacitor.
Calculate:
(a) the initial charge on the 20μF capacitor
(b) the capacitance of the parallel combination
(c) the p.d. across the parallel combination.

Attached is the page of the book showing the question diagram.

enter image description here

I am struggling to understand how the diagram on the bottom shows a parallel combination. I thought that this would be a series combination as the current can only go in one loop.

Can anyone offer an explanation why the diagram says this is a parallel combination?

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The capacitors are symmetrical (if they are not electrolyte capacitors). Thus connecting a second uncharged capacitor to the first charged one in series and shorting the ends produces two capacitors in parallel. This can also be deduced from the circuit diagram.

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If the two capacitors had different voltages on their connected plates, then current would flow between them. But the diagram specifies a fixed voltage drop $V$ from one side of the loop to the other. This means that the capacitors' connected plates are at the same voltage, so current can't flow in a loop; it can only flow across the plates of the capacitor.

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In theory, i.e. in the case of ideal capacitors, without resistances or inductivities involved, the capacitors are strictly parallel, which is a contradiction, since the initial value/voltage of the differential equation would be defined to be 9Volt and 0Volt at the same time. The paralleled capacitors can be seen to be 1 capacitor after connection, having 9V and 0V at the same time. So this case is impossible and the author of the book may not be aware of this fact. In reality, there are always resistors, inductivities, spark gaps, other capacities involved, i.e. these 2 capacitors are not connected in parallel, but in series. refer to the answer in Calculating the energy for a capacitor.

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