Physics question help capacitance

Please could I have help on question bii on page 2? The ms says discussion of why all charge of one sign is on one plate and then says the capacitance is 8*10-6 but isn’t it 12*10-6?
Paper: https://drive.google.com/file/d/1CXKH4JE0xvljYsbiDdc3cs-47P0rBqI2/view
Thanks!

Reply 1

Drummy

Original post by anonymous56754

so the combined capacitance is 8 microF isn't it

the charge that flows onto the combined capacitance is Q=CV = 72 microC

all of this flows onto one plate of X and off the other
what flows off is shared between Y and Z

the charge on X is therefore 72 microC (and the voltage across it 6V)
and the charge on Y or Z is 36 microC and their voltages 3V

Reply 2

Eimmanuel

Study Forum Helper

Original post by anonymous56754

It seems that you are confused on the principles and concepts of capacitors are connected in parallel or series:

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If two or more capacitors are connected in parallel, the potential difference is the same across all capacitors.

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If two or more capacitors are connected in series, the charge is the same on all capacitors.

I believe you know how to attempt (b)(i).
Consider the effective capacitance for Y and Z to be C_YZ, when capacitor X is in series with capacitor YZ of capacitance C_YZ, the capacitor X and YZ each has same charge Q while sum of the p.d. across X and YZ is equal to 9.0 V.

To find the charges on X, we can use either

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the effective capacitance X, Y and Z (8.0 μF) and total p.d. (9.0 V)