We have discussed waves traveling through a uniform medium. We now consider how a
traveling wave is affected when it encounters a change in the medium. For example,
consider a pulse traveling on a string that is rigidly attached to a support at one end as
in Figure 16.14. When the pulse reaches the support, a severe change in the medium
occurs—the string ends. The result of this change is that the pulse undergoes reflection—
that is, the pulse moves back along the string in the opposite direction.