Question

An AC source of RMS voltage 20 V with internal impedance ZS = (1+2j) Ω feeds a load of impedance ZL = (7+4j) Ω in the circuit given below. The reactive power is _________ (a) 8 VAR (b) 16 VAR (c) 28 VAR (d) 32 VAR The question was asked in an online interview. Asked question is from Advanced Problems on Network Theory in portion Network Theory and Complex Circuit Diagram of Network Theory Select the correct answer from above options network theory questions and answers, network theory questions pdf, network theory question bank, network theory gate questions and answers pdf, mcq on network theory pdf, gate network theory questions and solutions, network theory mcq Test , ies network theory questions, Network theory Questions for GATE EC Exam, Network Theory MCQ (Multiple Choice Questions)

Answer 1

Right answer is (b) 16 VAR Easy explanation: Current I = \frac{V}{Z_L+Z_S} = \frac{20∠0°}{8+6j} = \frac{20}{\sqrt{8^2+6^2}} = \frac{∠0°}{∠arc tan⁡(\frac{3}{4})} = \frac{20}{10} ∠-arc tan⁡(\frac{3}{4} ) = 2∠-arc tan⁡(\frac{3}{4} ) Power consumed by load = |I|^2ZL = 4(7+4j) = 28 + j16 ∴ The reactive power = 16 VAR.