What is capacitive reactance (XC)?

Capacitive reactance, denoted as XC, is defined as the opposition to the flow of alternating current (AC) caused by the presence of capacitance within a circuit. This phenomenon occurs because capacitors store and release energy in the form of an electric field. In an AC circuit, capacitors react to the change in voltage, which results in a phase difference between the voltage and current. The greater the frequency of the AC signal, the lower the capacitive reactance, allowing more current to flow through the circuit.

The formula for capacitive reactance is XC = 1 / (2πfC), where 'f' is the frequency of the AC source and 'C' is the capacitance in farads. This relationship illustrates that as frequency increases, XC decreases, emphasizing the frequency-dependent nature of capacitive reactance.

Understanding capacitive reactance is essential for interpreting how capacitors behave in AC circuits, and it differentiates from other circuit parameters, such as resistance in DC circuits, which do not incorporate phase shifts and operate under entirely different principles.