COMPOSITION OF NONSINUSOIDAL WAVESPure sine waves are basic wave shapes from which other wave shapes can be constructed. Anywaveform that is not a pure sine wave consists of two or more sine waves. Adding the correct frequenciesat the proper phase and amplitude will form square waves, sawtooth waves, and other nonsinusoidalA waveform other than a sine wave is called a COMPLEX WAVE. You will see that a complexwave consists of a fundamental frequency plus one or more HARMONIC frequencies. The shape of anonsinusoidal waveform is dependent upon the type of harmonics present as part of the waveform, theirrelative amplitudes, and their relative phase relationships. In general, the steeper the sides of a waveform,that is, the more rapid its rise and fall, the more harmonics it contains. The sine wave which has the lowest frequency in the complex periodic wave is referred to as theFUNDAMENTAL FREQUENCY. The type and number of harmonics included in the waveform aredependent upon the shape of the waveform. Harmonics have two classifications EVEN numbered andODD numbered. Harmonics are always a whole number of times higher than the fundamental frequencyand are designated by an integer (whole number). For example, the frequency twice as high as thefundamental frequency is the SECOND HARMONIC (or the first even harmonic). View (A) of figure 4-25 compares a square wave with sine waves. Sine wave K is the samefrequency as the square wave (its fundamental frequency). If another sine wave (L) of smaller amplitudebut three times the frequency (referred to as the third harmonic) is added to sine wave K, curve M isproduced. The addition of these two waveforms is accomplished by adding the instantaneous values ofboth sine waves algebraically. Curve M is called the resultant. Notice that curve M begins to assume theshape of a square wave. Curve M is shown again in view (B).