Practice question

**Current relative to voltage** in resistor in phase, φ=0°, power factor cos φ=1, maximum power, unlike inductor/capacitor where average power zero due to 90° phase shift, explaining why resistor heats while pure L/C does not. In an RL series circuit, impedance Z = √(R² + X_L²) , where X_L = ω L . Decreasing frequency reduces ω , lowering X_L , which decreases the impedance since R remains constant. 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 It decreases, consistent with phasor analysis and resonance condition X_L = X_C.