Three capacitors are connected in parallel. Each has plate area A and plate spacing d. We have to work out (a) the spacing of a single capacitor of plate area A if its capacitance equals that of the parallel combination. We will also work out (b) the spacing of a single capacitor of plate area A if its capacitance equals that of the series combination.

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(a)

Capacitance of a parallel plate capacitor of plate area A and plate spacing d is

.

When the three identical capacitors are connected in parallel the equivalent capacitance of the combination will be

Therefore, the spacing of a single capacitor of plate area A having the capacitance will have to be .

(b)

When the three identical capacitors are connected in series, the equivalent capacitance of the combination will be

Therefore, the spacing of a single capacitor of plate area A having the capacitance will be 3d.