Opposite of Resistors - Capacitors & Stored Charge Step by Step

Capacitor combination rules are the dual of resistor combination rules. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Use the same two capacitances

Compare 3 farads and 6 farads in different topologies.

C_a = 3\ \text{F}\qquad C_b = 6\ \text{F}

Series uses reciprocals

In series, the equivalent capacitance is 2 farads.

C_{\text{series}} = 2\ \text{F}

Parallel adds directly

In parallel, the equivalent capacitance is 9 farads.

C_{\text{parallel}} = 9\ \text{F}

The topology decides which number is large

For the same capacitor values, series gives the smaller equivalent capacitance and parallel gives the larger one. The middle row is the pair drawn in the diagrams.

\begin{array}{c|c|c|c}C_a&C_b&C_s&C_p\\2\ \text{F}&2\ \text{F}&1\ \text{F}&4\ \text{F}\\3\ \text{F}&6\ \text{F}&2\ \text{F}&9\ \text{F}\\4\ \text{F}&4\ \text{F}&2\ \text{F}&8\ \text{F}\\\end{array}