Calculate the total impedance and phase angle of a series RLC circuit at a specific frequency.
Last updated: March 2026 | By ForgeCalc Engineering
Impedance (Z) is the total opposition that a circuit presents to alternating current (AC). It is a complex quantity that combines resistance (R) and reactance (X). Unlike DC resistance, impedance depends on the frequency of the AC signal.
The phase angle (φ) represents the time shift between the voltage and the current. In an inductive circuit, voltage leads current (positive phase), while in a capacitive circuit, current leads voltage (negative phase).
Where:
• X_L = 2πfL (Inductive Reactance)
• X_C = 1 / (2πfC) (Capacitive Reactance)
• R is resistance (Ω)
• f is frequency (Hz)
Reactance is the opposition to AC caused by inductors and capacitors. It doesn't dissipate energy like resistance; instead, it stores and releases energy in magnetic or electric fields.
Inductors oppose high frequencies more (X_L increases with f), while capacitors oppose low frequencies more (X_C decreases as f increases). This makes RLC circuits useful for filtering.
A phase angle of 0° means the circuit is purely resistive. This happens at the resonant frequency, where X_L and X_C perfectly cancel each other out.
It's a mnemonic: E (Voltage) leads I (Current) in an L (Inductor). I (Current) leads E (Voltage) in a C (Capacitor).
Related Tools
Calculate AC power.
Calculate power consumption.
Convert conductivity to resistivity.
Calculate Curie constant.
Calculate Curie's Law.
Calculate cyclotron frequency.