Question

In an alternating circuit, the impressed voltage is given by V = (100 − j50) volts and the current in the circuit is I = (3 – j4) A. Determine the real and reactive power in the circuit.

Answer 1

Power will be found by the conjugate method. Using current conjugate, we have

P_VA = (100 − j50) (3 + j4) = 300 + j400 − j150 + 200 = 500 + j 250

Hence, real power is 500 W and reactive power of VAR is 250. Since the second term in the above expression is positive, the reactive volt-amperes of 250 are inductive.