Complex and irregular waveforms
The shape of an ac wave can get exceedingly complicated, but as long as it has a definite
period, and as long as the polarity keeps switching back and forth between positive
and negative, it is ac.
Fig. 9-6 shows an example of a complex ac wave. You can see that there is a period,
and therefore a definable frequency. The period is the time between two points on succeeding
wave repetitions.
With some waves, it can be difficult or almost impossible to tell the period. This is
because the wave has two or more components that are nearly the same magnitude.
When this happens, the frequency spectrum of the wave will be multifaceted. The energy
is split up among two or more frequencies.
