kapazitive

Kapazitive, in English usually written capacitive, describes phenomena or devices related to capacitance—the ability of a system to store electrical energy in an electric field between conductors separated by a dielectric. The basic property is capacitance C, defined as the charge Q stored per unit voltage V, C = Q/V, with the SI unit the farad. For a simple parallel-plate capacitor, C = εA/d, where ε is the permittivity of the dielectric, A is the plate area, and d is the separation.

In alternating current (AC) circuits, capacitors present an impedance Z = 1/(jωC). The current leads the voltage by 90 degrees in a pure capacitance. A capacitor blocks direct current (DC) after charging, but allows AC to pass, with the impedance decreasing as frequency increases.

Common uses include energy storage, filters and timing in RC circuits, decoupling of supply voltages, and coupling in signal paths. The term "capacitive" is also used for devices that sense or measure capacitance.

Capacitors come in many types and constructions: ceramic, electrolytic, film, mica, and variable capacitors. They differ in dielectric material, voltage rating, tolerance, and size. Dielectric losses, leakage, and parasitic elements affect performance, especially at high frequencies or high voltages.

Capacitive sensing relies on small changes in capacitance caused by proximity of a conductor such as a finger. Capacitance is a fundamental parameter in electronics and metrology, standardized in units and methods of measurement.