Capacitors in series:
When three capacitors are connected in series. If one electron moves from the negative terminal of the cell to the right hand plate of C_{3}, and one electron moves from the left hand plate of C_{1} to the positive terminal of the cell, one electron will move between C_{1} and C_{2} and between C_{2} and C_{3}. Thus, the total charge moved is one electron and the charge on each capacitor is one electron. Thus:
Q_{TOTAL} = Q_{1} = Q_{2} = Q_{3}
but V = V_{1} + V_{2} + V_{3 } (Kirchoff's second law)
also V = Q/C
Therefore Q/C_{TOTAL} = Q/C_{1} + Q/C_{2} + Q/C_{3} _{ }
Hence
Therefore, the three single capacitors may be replaced by a single capacitor whose capacitance (C) is given by the above equation, provided its safe working voltage is of a sufficiently high value to withstand the applied voltage.