What is capacitive reactance?

Capacitive reactance refers to the opposition that a capacitor presents to alternating current (AC). Unlike direct current (DC), which encounters no opposition from a capacitor once it is fully charged, alternating current changes direction, causing the capacitor to charge and discharge repeatedly. The formula for capacitive reactance is Xc = 1/(2πfC), where Xc is the capacitive reactance, f is the frequency of the AC signal, and C is the capacitance.

In AC circuits, capacitive reactance plays a crucial role in determining how capacitors impact the flow of current. As frequency increases, capacitive reactance decreases, allowing more current to flow through the capacitor. This characteristic is essential in various applications, including filtering and timing circuits, where the behavior of capacitors in response to AC signals is exploited.

The other choices do not accurately define capacitive reactance. The resistance a capacitor offers to direct current would not qualify as reactance since DC does not cause capacitors to open or close their paths. The total resistance in a circuit encompasses both resistive and reactive components but does not specifically refer to capacitive reactance alone. Additionally, the voltage across a capacitor is an important measurement but does not define the concept of