Practice question

**Impedance behavior at high frequencies** X_L=ωL dominates ∝ f, X_C=1/ωC →0, so Z≈√(R²+X_L²)≈X_L large, current small, circuit inductive, φ→90°, at low frequencies X_C large, Z≈X_C, capacitive, φ→-90°, at intermediate resonance Z minimal =R. Impedance: Z = √(R² + (X_L - X_C)²) . Z = √(50² + (30 - 20)²) = √(2500 + 100) = √(2600) ≈ 51 Ω . Applying X_L = ωL, X_C = 1/ωC, Z = √(R² + (X_L - X_C)²), I_rms = V_rms/Z, P = V_rms I_rms cosφ, V_s/V_p = N_s/N_p, calculation gives 50 Ω, consistent with phasor analysis and resonance condition X_L = X_C.