Calculate (a) the impedance of the circuit shown on the right, and (b), the current flowing through the circuit.

Solution:

1. The impedance, Z = = {R² + (X_L - X_C)²}^½.

   R² = 400 Ω ²
   X_L = 2 x 3.14 x 50 x 0.01 = 3.14 Ω
   X_C = 1/(2 x 3.14 x 50 x 30x10^-6) = 106 Ω
   from which Z = {400 + (3.14 - 106)²}^½ = (400 + 10580)^½ = 105 Ω.

2. The current is V_RMS/Z = 220 V/105 Ω = 2.1 A.