Capacitive Reactance

on . Posted in Electrical Engineering

Capacitive reactance, abbreviated as \(X_c\), is the opposition to holding an electric charge.

Key points about capacitive reactance

  • Inversely Proportional to Frequency  -  Capacitive reactance is inversely proportional to the frequency of the AC signal.  As the frequency increases, the capacitive reactance decreases, and vice versa.
  • Impedance in AC Circuits  -  Impedance is a measure of the total opposition that a circuit presents to the flow of AC.
  • Phasor Representation  -  Like resistance in DC circuits, capacitive reactance can be represented as a phasor in the complex plane.  The angle of the phasor is determined by the phase relationship between the voltage across the capacitor and the current flowing through it.
  • Units  -  Capacitive reactance is measured in ohms, the same unit as resistance.
  • Role in Filtering  -  Capacitors and their associated capacitive reactance play a crucial role in filtering applications in electronics.

Remember that capacitive reactance is associated with capacitors in AC circuits, and it is part of the broader concept of impedance in AC circuit analysis.

 

Capacitive Reactance formula

\( X_c =   1 \;/\; 2 \; \pi \; f \; C \)     (Capacitive Reactance)

\( f =   1 \;/\; 2 \; \pi \;  X_c \; C \)

\( C =   1 \;/\; 2 \; \pi \; f \; X_c \)

Symbol English Metric
\( X_c \) = capacitive reactance - \(kg-m^2\;/\;s^3-A^2\)
\( \pi \) = Pi   \(3.141 592 653 ...\)
\( f \) = frequency - \(s^{-1}\)
\( C \) = capacitance - \(s^4-A^2\;/\;kg-m^2\)

 

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Tags: Electrical