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Active vs. reactive power
A 60 Hz source feeding a series R-L load — watch the current lag the voltage and split the source's power into active P and reactive Q.
A 100 V RMS, 60 Hz source drives a resistor (8 Ω) in series with an inductor (16 mH, about 6 Ω of reactance at 60 Hz). The source measures its own active power P and reactive power Q, and two Meters on the canvas show their values. Press Run and compare the two sub-plots: the top one shows the source voltage V_src and the branch current I, the bottom one shows P and Q settling.
The current peaks about 37° after the voltage: that lag is the inductor's doing. Only the resistor turns energy into heat, so P ≈ I²R ≈ 800 W. The inductor stores energy and hands it back every half cycle; Q ≈ I²X ≈ 600 VAr measures that back-and-forth, which loads the source without doing any work. Together they give a power factor of P / √(P² + Q²) ≈ 0.8 lagging.
P and Q start from zero and settle over the first few tenths of a second because the source low-pass filters them (pq_time_constant = 0.07 s) to remove the twice-line-frequency ripple of the instantaneous power. Try setting the inductance to 0: Q drops to zero and the current moves back in phase with the voltage. Raise it and the current lags further while P falls, since the larger impedance draws less current.