Capacitifs

Capacitifs, in French usage, refer to capacitors, passive electronic components that store energy in an electric field. They are used for energy storage, signal coupling and filtering, and power conditioning.

A capacitor consists of two conductive plates separated by a dielectric. The capacitance C measures the ability to store charge per unit voltage and is determined by plate area, distance between plates, and the dielectric constant: C = εr ε0 A / d. The energy stored at voltage V is E = 1/2 C V^2.

Common types include electrolytic capacitors (high capacitance, often polarized), ceramic capacitors (small, stable, widely used for decoupling), film capacitors (polyester, polypropylene, stable and reliable), tantalum capacitors (a polarized electrolytic with specific properties), and supercapacitors (ultracapacitors with very high capacitance for rapid energy storage). There are also variable capacitors used in tuning circuits.

Key characteristics include capacitance value (from picofarads to farads), voltage rating, tolerance, equivalent series resistance (ESR), leakage current, and temperature coefficient. Polarized types require correct polarity and care to avoid damage.

Applications cover power-supply filtering and smoothing, energy storage in memory backups or pulsed devices, coupling and decoupling of signals, timing and waveform shaping, audio and RF circuits, and, in some cases, renewable energy storage.

History: The concept dates to Leyden jars in the 18th century; modern capacitors emerged with dielectric materials and industrial manufacturing in the 20th century.

See also: Dielectric, Capacitance, Electronic components, Energy storage devices.

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