key term - Capacitive reactance

Definition

Capacitive reactance is the opposition that a capacitor presents to alternating current. It is inversely proportional to both the frequency of the AC signal and the capacitance.

5 Must Know Facts For Your Next Test

1. Capacitive reactance ($X_C$) is given by the formula $X_C = \frac{1}{2\pi f C}$, where $f$ is the frequency in hertz and $C$ is the capacitance in farads.
2. The unit of capacitive reactance is ohms (Ω).
3. As frequency increases, capacitive reactance decreases.
4. Capacitive reactance causes a phase shift where the current leads the voltage by 90 degrees in an ideal capacitor.
5. In AC circuits, capacitive reactance impacts the total impedance.

Review Questions

Related terms

Inductive Reactance:

The opposition that an inductor presents to alternating current, proportional to both frequency and inductance. It causes current to lag behind voltage by 90 degrees.

Impedance:

The total opposition that a circuit presents to alternating current, composed of both resistance and reactance.

Capacitance:

\(The ability of a system to store charge per unit voltage; measured in farads (F).\)