Like the title says, my task is to find the initial voltage across the terminals. The two capacitors are in Series with positive end of one plate connected to that of another.

The given information are:

\$C_1\$ = 12 microFarad, \$V_1\$ = 6 Volts, \$C_2\$ = 4 microFarad, \$C_2\$ = 2 Volts.

The circuit diagram is:

enter image description here

I have calculated the equivalent capacitance and I just need the total charge in the circuit to find the total or initial voltage using the equation,

Q = C*V

So, I first attempted to find \$Q_1\$ = \$C_1\$ * \$V_1\$ = 72 microCoulomb.

\$Q_2\$ = \$C_2\$ * \$V_2\$ = 8 microCoulomb.

I know that the positive charges accumulate on the positive end of the capacitor,

Hence, I am unsure whether \$Q_T\$ or Total Charge in the circuit = \$Q_1\$ + \$Q_2\$ or the difference between the two charges which is |\$Q_1\$ - \$Q_2\$|?

  • 1
    \$\begingroup\$ That top capacitor is very dead. The symbol says it's a polarized capacitor, but it's got 6 V on it in the reverse direction; I don't think it's going to remain a capacitor for very long. \$\endgroup\$
    – Hearth
    Jun 25, 2023 at 14:35
  • 1
    \$\begingroup\$ It's an open circuit - no current is flowing and the charges on the capacitors have not equalized. \$\endgroup\$
    – brhans
    Jun 25, 2023 at 15:34

1 Answer 1


my task is to find the initial voltage across the terminals.

You are overthinking this; it's quite simply 2 volts minus 6 volts or, 6 volts minus 2 volts if your reference node is at the top.


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