- In this article, we discuss how capacitors are connected in series, and also find the equivalent capacitance of capacitors connected in series.
- We also discuss the effects of series connection of capacitors on the charge storage capacity.
- Finally we discuss why the capacitors are connected in series in practice.
When capacitors are connected as shown in the figure below, they are said to be connected in series. In series connection of capacitors, the capacitors are connected in a chain-like fashion.
Charge stored by each capacitor in series connection in same :If a voltage source is applied to the series combination of capacitors, then the current has only one path to flow. Hence the charge stored by every capacitor in the series chain is same. To understand this in a better way, consider the positive plate of capacitor C1 where positive charge +Q is supplied by the battery. As one plate is positively charged, it induces -Q charge on the second plate of C1. As the plates of C1 and C2 are connected with each other, +Q charge will be established on the near plate of C2.This induces -Q charge on the second plate of C2. This continues further. Hence we can say that all the capacitors connected in series have equal charge. Although all the capacitors connected in series have equal charge, the voltages across each capacitor will be different. This is because each capacitor connected in series have different capacitances. If we denote the voltage across Capacitor C1 as V1, voltage across C2 as V2 and so on, then from the figure it is clear that.
V = V1 + V2 + V3.
If the equivalent capacitance is denoted by C, then.
This formula indicates that the effective value of capacitance of series connection of capacitors is less than the least value of capacitance in the combination.Things are better understood with examples. So consider the following example.
Example : Three capacitors of 0.2μF, 0.4μF and 0.6μF are connected in series. Calculate the effective capacitance.
Solution :The effective capacitance is given by the relation C-1=C1-1+C2-1+C3-1. Putting the value of C1, C2 and C3, we get C=0.11μF. This is less than the least value of capacitor connected in series, which is 0.2μF.
When are the capacitors connected in series? We have seen that the effective value of capacitance decreases when capacitors are connected in parallel. So question must arise as to why do we connect capacitors in series. One reason you might want to connect capacitors in series is to increase the working voltage. If you connect two identical capacitors in series whose maximum voltage rating is 200 V, you can increase the working voltage to 400 V.