Definition
An electrical component that stores energy in an electric field by holding opposite electrical charges on two conductive plates separated by an insulating material called a dielectric. A capacitor opposes changes in voltage, can block direct current while allowing alternating current to pass, and releases its stored charge back into the circuit when needed.
Plain English
A small part in an electrical circuit that holds an electrical charge for a short time and then releases it. Think of it as a tiny, fast rechargeable reservoir for electricity.
Context Anchor
Seen in aircraft electrical system maintenance, radio and instrument circuits, and ignition-system discussions.
Derivation
From the Latin 'capacitas,' meaning 'capacity' or 'ability to hold.' The name describes exactly what the part does — it has the capacity to hold an electrical charge.
Why Pilots Care
Capacitors are found in ignition systems, radios, and many avionics units. A failed capacitor is a common cause of rough magneto operation, radio noise, or instrument faults, so the term comes up often in squawks and maintenance discussions.
Analogy
A capacitor is like a small spring in an electrical circuit. It compresses (stores energy) when voltage is applied, and pushes back (releases energy) when the voltage drops.
Intuition Check
A capacitor is not a battery. A battery stores chemical energy for longer use; a capacitor stores electric charge for short, quick use in a circuit.
Example Sentence 1
The mechanic traced the magneto's rough running to a failed capacitor and replaced it during the 100-hour inspection.
Example Sentence 2
During preflight checks a technician measures the capacitor to confirm it holds charge properly for the electrical system.