What is capacitive reactance and how is it calculated?

Capacitive reactance is the opposition to the flow of alternating current by a capacitor.

Capacitive reactance is a measure of the opposition to the flow of alternating current by a capacitor. It is denoted by Xc and is measured in ohms. Capacitive reactance depends on the frequency of the alternating current and the capacitance of the capacitor. The higher the frequency, the lower the capacitive reactance, and the higher the capacitance, the lower the capacitive reactance.

Capacitive reactance can be calculated using the formula Xc = 1/(2πfC), where f is the frequency of the alternating current in hertz and C is the capacitance of the capacitor in farads. This formula shows that capacitive reactance is inversely proportional to the frequency and directly proportional to the capacitance.

To understand more about how capacitors function within circuits, see Capacitance of Isolated Spherical Conductors.

Capacitive reactance plays an important role in AC circuits that contain capacitors. It limits the flow of current through the capacitor and affects the phase relationship between the voltage and current. Capacitive reactance can also be used to calculate the impedance of a circuit that contains a capacitor. For a deeper understanding of impedance in AC circuits, refer to Characteristics of Alternating Currents (AC Waveform Parameters).

The concept of electric fields is integral to understanding how capacitors and their reactance operate in circuits. Learn more at Electric Field Basics.

A-Level Physics Tutor Summary: Capacitive reactance is the resistance a capacitor offers to alternating current, calculated by the formula Xc = 1/(2πfC). It varies with the frequency (f) and capacitance (C) of the capacitor; lower frequency and lower capacitance result in higher reactance. This concept is crucial for understanding AC circuit behaviour, including current flow and voltage-current phase relationships.