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the left plate of C 2 causes negative charges to accumulate on the right plate of C 1 . As a result, all the right plates end up with a charge $ Q , and all the left plates end up with the charges on capacitors connected in series are the same. From Figure 26.10a, we see that the voltage !V across the battery terminals is split between the two capacitors: (26.9) where !V 1 and !V 2 are the potential differences across capacitors C 1 and C 2 , respectively. In general, the total potential difference across any number of capacitors connected in series is the sum of the potential differences across the individual capacitors. Suppose that the equivalent single capacitor in Figure 26.10c has the same effect on the circuit as the series combination when it is connected to the battery. After it is Because we can apply the expression Q # C !V to each capacitor shown in Figure Substituting these expressions into Equation 26.9, we have Canceling Q , we arrive at the relationship When this analysis is applied to three or more capacitors connected in series, the (26.10) This shows that the inverse of the equivalent capacitance is the algebraic sum of the inverses of the individual capacitances and the equivalent capacitance of a series 1 C
eq # 1 C
1 & 1 C
2 & 1 C
3 & + + +
(series combination) 1 C
eq # 1 C
1 & 1 C
2
(series combination) Q C eq # Q C 1 & Q C
2 ∆V 1 # Q C 1
∆V 2 # Q C
2 ∆V # Q C eq ∆V # ∆V 1 & ∆V 2 SECTION 26.3 • Combinations of Capacitors 805 Quick Quiz 26.3 Two capacitors are identical. They can be connected in series or in parallel. If you want the smallest equivalent capacitance for the combina- Quick Quiz 26.4 Consider the two capacitors in Quick Quiz 26.3 again. Each capacitor is charged to a voltage of 10 V. If you want the largest combined poten- Capacitors in series |