Which power is defined as the vector sum of real and reactive power?

• A. Real power
• B. Apparent power
• C. Reactive power
• D. None of these

Answer: (B)

Apparent power is the combination of real power and reactive power, because in AC systems these two components are 90 degrees out of phase. They form a right triangle where P and Q are the legs and S, the magnitude of the total power flow, is the hypotenuse: S = sqrt(P^2 + Q^2). In practice, apparent power also equals V_rms times I_rms, and it’s represented in complex form as S = P + jQ, with units of volt-amperes (VA). Real power is the actual power dissipated as heat or doing work, while reactive power stores and releases energy; the vector sum gives the total power the system can deliver at a given voltage and current.