Variable capacitor

A capacitor whose capacitance can be adjusted, usually by changing the overlap or spacing of its conductive plates. Its adjustable capacitance is used to tune electrical circuits.

Capacitance: A measure of a system's ability to store electric charge per unit voltage. It is the electrical property that a variable capacitor changes.
Air capacitor: A capacitor that uses air as the insulating dielectric between conductors. Many traditional variable capacitors use air between interleaving plates.
LC circuit: A circuit containing an inductor and capacitor that can resonate at a frequency. A variable capacitor adjusts the resonance of an LC circuit.
Varactor: A semiconductor diode whose junction capacitance changes with applied reverse voltage. Unlike a plate-based variable capacitor, it adjusts electronically and has no moving parts.
Parallel-plate capacitor: A capacitor formed by two conductive plates separated by an insulating gap. Its capacitance changes with plate area and separation, the basic geometry behind many adjustable designs.
Rotor (electrical component): The rotating conductive part of an electromechanical component. Turning the rotor changes how far its plates overlap the stationary plates.
Superheterodyne receiver: A radio receiver that converts an incoming signal to a fixed intermediate frequency. Traditional receivers use variable capacitors to tune their local oscillator and input circuits.
Switched capacitor: A circuit technique that uses switched capacitors to emulate resistors or set signal-processing behavior. It changes effective capacitance through switching rather than continuous mechanical motion.
Dielectric: An electrical insulator that polarizes in an applied electric field. The material between the plates influences capacitance alongside their geometry.
Stator (electrical component): The stationary conductive part of an electromechanical component. Its fixed plates form the counterpart to the moving rotor plates.

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PotentiometerCompared with: It tunes resonant circuits by changing capacitance rather than resistance.