Capacitantie

Capacitantie, or capacitance in English, is the ability of a system to store electric charge per unit voltage. It is denoted by the symbol C and measured in farads (F). One farad equals one coulomb of charge stored per volt of potential difference.

The capacitance is defined as C = Q / V, where Q is the stored charge and V is the potential difference between conductors. The energy stored in a charged capacitor is U = 1/2 C V^2.

Capacitance depends on geometry and the material between conductors. It increases with plate area and with the dielectric’s permittivity, and decreases with the separation between plates. For a simple parallel-plate capacitor, C = ε ε0 A / d, where ε0 is the vacuum permittivity, ε is the relative permittivity of the dielectric, A is the plate area, and d is the separation.

In circuits, capacitance can be intrinsic to components (parasitic capacitance) or intentional (capacitors). Non-idealities include dielectric losses and leakage currents; temperature can alter the dielectric constant and thus the capacitance.

Applications of capacitance include energy storage, filtering, decoupling of power lines, and timing in analog and digital electronics. In alternating current analysis, the impedance is Z = 1 / (j ω C). Capacitance values span a wide range, from picofarads to farads, with common capacitors often in the nanofarad to microfarad range.

The term capacitance is used worldwide; the farad honours Michael Faraday. Capacitance is a foundational concept in electricity and electronics, complementing resistance and inductance.