Capacitors In Series:
With the capacitors, there is seldom any important mutual interaction. At very high ac frequencies, though, inter-electrode capacitance can at times be a problem for engineers. This result that shows up as an inherent tiny capacitance among wires which run near and parallel to each other is almost always undesirable in practical circuits.
Capacitors in series add altogether such as resistors or inductors in parallel. Whenever you join two capacitors of same value in series, the outcome is half the capacitance of any component alone. In common, when there are numerous capacitors in series, the compound value is less than that of any of the single components. It is significant that you always use the similar size units whenever determining the capacitance of any combination. Do not mix microfarads with picofarads. The outcome you acquire will be in whichever size units you use for the separate components.
Assume that you have numerous capacitors with values C1, C2, C3,..., Cn associated in series (as shown in figure below. You can find the reciprocal of the total capacitance 1/C by using the following formula:
1/C = 1/C1 +1/C2 +1/C3 ... 1/Cn
Figure: Capacitances in series add like resistances or inductances in parallel.
The total capacitance C is establishing by taking the reciprocal of the number you get for 1/C.