(This activity can be accessed at:
Waves are patterns of disturbance that travel
or "propagate" through a medium.
There is energy associated with wave disturbances, so they are capable of doing
damage or useful work.
Simple, regular wave patterns can be characterized by their wavelength,
wave height (amplitude), wave velocity or speed,
wave period, and wave frequency. Examples of waves in nature
are numerous: sound waves (which travel through air or water); water waves;
earthquake waves (which travel through rock); electromagnetic radiation such
as visible light, radio waves, microwaves, and X-rays (all of which travel through
There is a common confusion between (1) the motion of a wave disturbance; and
(2) the motion of "particles" of the medium through which the wave
disturbance travels. It is tempting to think of a moving wave crest as a material
object in its own right, but this is not generally correct. Rather, waves are
a traveling pattern of displacement or disturbance in a medium, while the "particles"
in the medium itself might oscillate as a wave passes through but ultimately
experience little or no net change in position at all. (Breaking waves in water
are an exception.) In this activity you will explore this distinction with the
help of a computer animation of deep water wave motions in idealized "water".
- distinguish between the motion of a wave disturbance in deep water and the
motion of "particles" of the water through which the wave travels
Instructions and Questions
You can carry out the steps below either on your own or together with someone
else. In class, be prepared for interruptions by the instructor to get and give
- Go to the following WWWeb site, created by Dr. Dan Russell of Kettering
University's Dept. of Applied Physics:
and Transverse Wave Motion"
Here you will find animations of four different types of waves:
- Longitudinal waves. (Examples include sound waves in air or
water, and the type of earthquake waves called P-waves. This kind of wave
tends to be relatively fast-moving, and the more dense the medium through
which they travel the faster they move.)
- Transverse waves. (An example is the type of earthquake wave
called S-waves or "shear" waves. These are slower than P-waves
and therefore arrive later. The perspective could be either a "map
view" looking down on the wave from above, or a cross-section view
looking at the wave from the side.)
- Water waves. (The ones shown here are characteristic of waves
in deep water. Waves in shallow water "feel" the bottom and
behave a little differently in some respects, though the basic idea is
the same until the shallow water waves begin to break.)
- Raleigh surface waves. (An example is the type of earthquake
wave called a surface wave; it's the kind of undulating wave that some
observers can see coming across the earth's surface immediately after
an earthquake. These are slower than P-waves and arrive later.)
- Take a closer look at the water waves (the third type above). Pick out
a wave "crest" and follow it. In which direction is the wave disturbance
- Focus on one "particle" of the medium and describe its motion.
(One of the two blue dots is easiest to follow.) How does it's motion compare
to the wave motion? How do the particle motions vary with depth?
- Focus on two particles of the medium that are next to each other, and describe
their motions relative to each other. Can you think of how the motions of
adjacent particles relative to each other might relate to the motion of the
wave disturbance in each case?
(For example, why does the water surface go up and down? What motions within
the water are required for this to happen?
It might help to imagine a narrow column extending from the water surface
down to the bottom, with water able to move in and out of the column through
the sides. How would (net) motions of water in and out of the column affect
the up/down motion of the water surface?)
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