Wave Phenomena

**Figure:** *Two views of a wave.*
$\begin{figure} \begin{center}\mbox{ \epsfig{file=PS/wave.ps,height=2.55in} % }\end{center}\end{figure}$

We can visualize a vivid example for the sake of illustration: suppose the ``amplitude'' A is the height of the water's surface in the ocean (measured from A=0 at ``sea level'') and x is the distance toward the East, in which direction waves are moving across the ocean's surface.^14.1 Now imagine that we stand on a skinny piling and watch what happens to the water level on its sides as the wave passes: it goes up and down at a regular frequency, executing SHM as a function of time. Next we stand at a big picture window in the port side of a submarine pointed East, partly submerged so that the wave is at the same level as the window; we take a flash photograph of the wave at a given instant and analyze the result: the wave looks instantaneously just like the graph of SHM except the horizontal axis is distance instead of time. These two images are displayed in Fig. 14.1.

Jess H. Brewer
1998-11-06