Capacitors in Series

When capacitors are connected end-to-end in series, the same charge must pass onto each capacitor, so each one stores the same magnitude of charge. The total voltage across the chain is the sum of the individual voltage drops, and because V = Q/C, the voltages add in a way that makes the reciprocals of the capacitances add. This means the series combination always has a capacitance smaller than the smallest single capacitor in the set.

Use this formula when you need the equivalent capacitance of capacitors connected in one continuous path, such as in circuit analysis, filter design, or when replacing several capacitors with a single equivalent component. It is especially useful whenever the capacitors are not connected across the same two nodes.

• Adding series capacitances directly instead of adding reciprocals
• Forgetting that the equivalent capacitance in series must be smaller than the smallest capacitor
• Mixing up series and parallel rules for capacitors and using the wrong formula