At what frequency is capacitive reactance equal to resistance?

You can work it out this way: set X_C = R and solve for f.

Find the resonant frequency for L=100mH, C=10μF.

You can work it out this way: use f₀ = 1/(2π√LC).

Pro 🔒~30 min

AC Circuits

Explore alternating current, capacitors, and inductors

How it works

In AC circuits, capacitors and inductors create frequency-dependent opposition called reactance. Capacitive reactance decreases with frequency while inductive reactance increases. At resonance, they cancel each other and only resistance limits current. Understanding AC circuits is essential for power systems, radio communications, and signal processing.

Upgrade to Pro to access this experiment

Step-by-step

Adjust frequency and observe how impedance changes.
At resonance frequency, current reaches its maximum.
The phasor diagram shows phase angles between voltage and current for each component.

Key formulas

$X_C = \frac{1}{2\pi f C}$ Capacitive reactance
$X_L = 2\pi f L$ Inductive reactance
$Z = \sqrt{R^2 + (X_L - X_C)^2}$ Impedance
$f_0 = \frac{1}{2\pi\sqrt{LC}}$ Resonant frequency

Frequently asked questions

At what frequency is capacitive reactance equal to resistance?: You can work it out this way: set X_C = R and solve for f.
Find the resonant frequency for L=100mH, C=10μF.: You can work it out this way: use f₀ = 1/(2π√LC).
How does power factor change near resonance?: Power factor = R/Z.