How to Use Capacitors in Electronic Circuits

A capacitor is a pair of conductors (plates) separated by an insulator (dielectric) that has capacity of storing an electric charge. A capacitor is frequently used in electronic circuits to temporarily store electrical energy. The following steps will show how capacitors work in electronic circuits.

Difficulty: Moderate

Instructions

1. Charge a capacitor from a battery. Electrons flow from the negative terminal of the battery to the negative plate on the capacitor. The charge on the electrode increases until the insulating limit (dielectric capacity) is reached. The capacitor is fully charged at this point.

2. Open the circuit between the battery and capacitor. The electron flow ceases when the circuit between the negative terminal of the battery and negative plate on the capacitor is broken. The capacitor retains its charge caused by the electrostatic force between the two plates.

3. Close a circuit between the negative and positive plates on the capacitor. Electrons flow from the negative to the positive plate of the capacitor until the charges on the plates are equal.

4. Use a capacitor in a circuit with direct current (DC) voltage. The current through the capacitor is the rate at which the charge and therefore the voltage changes over time. Because DC voltage is constant, DC does not pass through a capacitor.

5. Study a capacitor's operation in an alternating current (AC) circuit. The current flow in this type of circuit changes direction periodically (reverses polarity) and the current is non-zero except for the instant the polarity reversal occurs. A capacitor can therefore be said to "pass" AC.

Resources

• More about capacitors at The Gear Page