http://www.ck12.org Chapter 10. Periodic Motion
eyes and the light waves reflect off the mirror. It may not be obvious, but all waves can reflect. Water waves that
come up along the shore are partially reflected. Drop a pebble into still water as inFigure10.17 and you’ll see the
wave eventually reflect.
FIGURE 10.16
Light reflects off of a mirror.FIGURE 10.17
These waves will eventually reflect off the
sides of the pond.Sound waves reflect and cause echoes. If you go to a concert, you’ll notice that there are heavy drapes positioned
around the concert hall. The heavy material helps to absorb the sound energy, thus reducing the amount of reflected
sound which can negatively affect your listening pleasure! The fact that the drapes can absorb some of the sound
energy implies that some of the wave energy can be transmitted to another medium. We will study wave transmission
later.
Waves Undergo Refraction
Torefractmeans to bend. We usually associate the refraction of a wave with light, as inFigure10.18, but, again,
all waves can refract. It is very fortunate, indeed. If light waves could not be refracted, we could never form images
with microscopes or telescopes. Eye glasses could not exist. All of the optical phenomena we associate with lenses
would be impossible if light did not refract. We will study refraction and lenses in greater detail later.
An interesting phenomenon illustrating the bending of sound involves the temperature difference between a warm
road (asphalt) and the cooler air above the road. For our purpose, we state without explanation, that sound travels
faster through a warmer medium than through a cooler medium. Those sound waves closer to the road will move