When the voltages shown in Figure 1.1 and Figure 1.2 are applied to
electrical loads, the load currents will have frequency and amplitudes
dependent on the impedance or other characteristics of the load. If the
waveform of the load current is also sinusoidal, the load is termed
“linear.” If the waveform of the load current is distorted, the load is
termed “nonlinear.” The load current with distorted waveform can produce