Build series and parallel RLC networks; plot impedance magnitude and phase vs frequency
Impedance Z = R + jX extends resistance to AC circuits by including reactance. |Z| = √(R²+X²) gives the peak voltage-to-current ratio; phase angle θ = arctan(X/R) gives the phase shift.
Series: Z_total = Z1 + Z2 (add complex numbers directly). Parallel: 1/Z_total = 1/Z1 + 1/Z2.
Z = R + j(ωL − 1/ωC). At resonance ω₀ = 1/√(LC), imaginary parts cancel and Z = R. Bandwidth BW = f₀/Q.