If you ask which term is the vector sum of the components of AC opposition, the answer is:

• A. Resistance, conductance, and susceptance
• B. The vector sum of resistance, capacitive reactance, and inductive reactance
• C. Resistance only
• D. Inductive reactance only

Answer: (B)

AC opposition is described by impedance, which combines a real part (resistance) with a reactive part from inductors and capacitors. Because voltage and current in AC circuits are usually out of phase, these components must be added as a vector (phasor) sum rather than simply adding magnitudes. The resistive part lies on the real axis, while the inductive and capacitive parts lie on the imaginary axis so that the net reactive part is X = X_L − X_C. The total impedance is Z = R + j(X_L − X_C). So the term that represents the vector sum of the components opposing AC current is the impedance—the vector sum of resistance, capacitive reactance, and inductive reactance. Conductance and susceptance relate to admittance, not the opposition to current.