When using rectangular coordinates to graph the impedance of a circuit, what do the axes represent?
Why Impedance is written as a complex number Z = R + jX, where R is the resistance and X is the reactance. On a rectangular (Cartesian) graph the real part goes on the horizontal axis and the imaginary part, marked by the j operator, goes on the vertical axis. So a point plotted at (50, 25) means 50 ohms of resistance with 25 ohms of inductive reactance. Reactance below the axis (negative) is capacitive.
Watch out Magnitude and phase angle are the polar coordinate description of the same impedance, not the rectangular axes; converting between the two forms is done with the Pythagorean theorem and the arctangent.
R + jX: R is real and rides the horizontal axis, jX is imaginary and goes up and down.