In Z = R + jX, what do R and X represent?

In Z = R + jX, what do R and X represent?

• A. R is the impedance's reactive component; X is resistance.
• B. R is the reactance; X is the resistance.
• C. R is the resistance; X is the reactance.
• D. R is the imaginary part; X is the real part.

Answer: (C)

Impedance is a complex quantity with a real part and an imaginary part. In Z = R + jX, the real part R is the resistance—the part of the impedance that dissipates energy as heat in a resistor. The imaginary part X, multiplied by the imaginary unit j, is the reactance—the part that stores and returns energy in inductors and capacitors, causing a phase shift between voltage and current. The sign of X tells you whether the net reactance is inductive (positive) or capacitive (negative). The magnitude of Z combines these parts as |Z| = sqrt(R^2 + X^2) and the phase angle is arctan(X/R). So the correct interpretation is that R is resistance and X is reactance.

Impedance is a complex quantity with a real part and an imaginary part. In Z = R + jX, the real part R is the resistance—the part of the impedance that dissipates energy as heat in a resistor. The imaginary part X, multiplied by the imaginary unit j, is the reactance—the part that stores and returns energy in inductors and capacitors, causing a phase shift between voltage and current. The sign of X tells you whether the net reactance is inductive (positive) or capacitive (negative). The magnitude of Z combines these parts as |Z| = sqrt(R^2 + X^2) and the phase angle is arctan(X/R). So the correct interpretation is that R is resistance and X is reactance.