What describes capacitive reactance?

Capacitive reactance refers specifically to the opposition that a capacitor presents to alternating current (AC) in a circuit. This opposition arises from the capacitor's ability to store and release energy in the form of an electric field, which is significantly different from resistance in a resistor. The value of capacitive reactance decreases as the frequency of the AC signal increases, making it frequency-dependent.

In practical terms, when an alternating voltage is applied across a capacitor, it does not allow current to flow freely like a resistor would; instead, it stores energy and releases it in a cyclical manner, which results in a phase shift between the voltage and current. This is critical in AC circuits where capacitors are often used for filtering, timing applications, or in resonant circuits.

Understanding capacitive reactance is vital in the design and analysis of electrical systems, as it influences how capacitors interact with other circuit elements.