Problem 3.113

Four identical metal plates are located in air at equal distances $d$ from one another. The area of each plate is equal to $S$ . Find the capacitance of the system between points $A$ and $B$ if the plates are interconnected as shown (a) in Fig. 3.18a; (b) in Fig. 3.18b.

\text { (a) } C=2 \varepsilon_{0} S / 3 d ; \text { (b) } C=3 \varepsilon_{0} S / 2 d \text { . }

Electric Capacitance, Energy of an Electric Field