Capacitors

A tiny, temporary battery that charges and discharges fast.

A capacitor stores electrical energy in an electric field between two conductive plates separated by an insulator. It charges up when voltage is applied and releases that charge when the voltage drops — smoothing out sudden dips or spikes.

• Measured in farads — practical values are usually microfarads (µF) or picofarads (pF).
• Electrolytic capacitors (often cylindrical) have polarity — one leg must go to the more positive side.
• Common uses: smoothing power supplies, filtering noise, timing circuits.