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_L = ω L , ω = 2π × 60 = 376.8 rad/s . L = 70 × 10⁻³ H . X_L = 376.8 × 0.07 = 26.38 Ω . RMS current: I = (V/X_L) = (230/26.38) ≈ 8.72 A . Peak current: i_m = √(2) I = 1.414 × 8.72 ≈ 12.33 A . Applying X_L