Impedance Calculator

An RLC circuit is an electrical circuit containing a resistor (R), an inductor (L), and a capacitor (C) connected in series or parallel. These circuits are widely used in radio receivers, televisions, filters, and oscillators because of their frequency-selective behavior.

For a series RLC circuit, impedance is calculated as Z = √(R² + (XL − XC)²), where XL = 2πfL is the inductive reactance and XC = 1/(2πfC) is the capacitive reactance. The result is in ohms (Ω).

For a parallel RLC circuit, the admittance Y = √((1/R)² + (1/XL − 1/XC)²), and impedance Z = 1/Y. At resonance, a parallel RLC circuit has maximum impedance, which is the opposite behavior of a series circuit.

Impedance (Z) is the total opposition that a circuit offers to alternating current, measured in ohms. It combines resistance (purely dissipative) with reactance (frequency-dependent, from inductors and capacitors) into a single complex quantity.

Yes. Resistance (R) is a constant component of impedance and does not change with frequency. Reactances XL and XC are frequency-dependent. The total impedance Z = √(R² + (XL − XC)²) for a series circuit, so both resistance and reactance together determine Z.

The resonant frequency is f₀ = 1 / (2π√(LC)), where L is inductance and C is capacitance. At resonance, XL equals XC, and the impedance of a series circuit is at its minimum (equal to R alone), while a parallel circuit reaches maximum impedance.

The phase angle φ describes the phase difference between the voltage and current in the circuit. It is calculated as φ = arctan((XL − XC) / R) for a series circuit. A positive angle means the circuit is inductive; negative means capacitive; zero means resistive (at resonance).

The Q factor (quality factor) measures how underdamped a resonator is, or how narrow its resonant bandwidth is. For a series RLC circuit, Q = (1/R)√(L/C). A higher Q factor means sharper resonance and lower energy loss relative to stored energy.