Practice question

**AC through inductor** voltage leads current by 90°, V = L dI/dt, V(t)=V_peak sin(ωt+90°), I(t)=I_peak sin ωt, instantaneous power P= V I =½ V_peak I_peak sin2ωt, average zero over cycle because energy stored in magnetic field ½ L I² returned to source each quarter cycle, no net dissipation. X_C = (1/ω C) , ω = 2π × 60 = 376.8 rad/s . C = 18 × 10⁻⁶ F . X_C = (1/376.8 × 18 × 10⁻⁶) ≈ 147.3 Ω . RMS current: I = (V/X_C) = (110/147.3) ≈ 0.747 A . Applying X_L = ωL, X_C = 1/ωC, Z = √(R² + (X_L - X_C)²),