Trough, of wave

The crimp imparted to the tow has a sawtooth or sinusoidal wave shape. Because the filaments are usually crimped as a group, the crimp in parallel fibers is in lateral registry, ie, with the ridges and troughs of the waves aligned, as shown in Figure 14. 

Wavelength (Section 13.1) Distance between two successive maxima (peaks) or two successive minima (troughs) of a wave. 

Frequency (v), the number of wave cycles (successive crests or troughs) that pass a given point in unit time. If 108 cycles pass a particular point in one second,... 

FIGURE 1.20 (a i Constructive interference. The two component waves (left) are "in phase" in the sense that their peaks and troughs coincide. The resultant (right) has an amplitude that is the sum of the amplitudes of the components. The wavelength of the radiation is not changed by interference, only the amplitude is changed, (b) Destructive interference. The two component waves are "out of phase" in the sense that the troughs of one coincide with the peaks of the other. The resultant has a much lower amplitude than either component. 

When two or more waves pass through the same region of space, the phenomenon of interference is observed as an increase or a decrease in the total amplitude of the wave (recall Fig. 1.20). Constructive interference, an increase in the total amplitude of the wave, occurs when the peaks of one wave coincide with the peaks of another wave. If the waves are electromagnetic radiation, the increased amplitude corresponds to an increased intensity of the radiation. Destructive interference, a decrease in the total amplitude of the waves, occurs when the peaks of one wave coincide with the troughs of the other wave it results in a reduction in intensity. 

Fig. 1J Illustrating the interference of two waves, spreading from different centres. Light and dark rings represent the crests and troughs of each wave. Regions of constructive Interference (where crests of each wave ooincfde) and of destmctive interference (where crests of one wave overlap with troughs of the other) can be seen.

As the name implies, electromagnetic waves exhibit all of the classical properties of waves. Figure 13.2 illustrates the various features of a simple wave. The wavelength, A (lower case Greek letter lambda), is the distance required for a wave to repeat itself. For instance, it is the distance between adjacent peaks (or crests) and also the distance between adjacent troughs. Wavelength is usually measured in meters. The period, T, is the time required for a wave to repeat itself. 

On the contrary, if the crest of one wave overlaps with the trough of the other, then two waves interact in a destructive manner. In other words, this is out of phase overlap or subtraction overlap and the resulting wave is weakened. Such type of subtraction overlap of atomic orbitals with opposite signs leads to the formation of antibonding molecular orbital. 

Wavelength (A) (Section 13.1) The distance of one complete cycle of the light wave the distance between successive crests or troughs of the wave. 

Fig. 9 shows two equal sets of waves moving in slightly different directions, indicated by the arrows. Points where two crests are superposed are marked +> and points where two troughs come together, —. Points where a trough and a crest are superposed are marked 0. We see that the + and — points lie on parallel lines, and that the 0 points lie in between. 

---