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Making Waves

When you look at an ocean wave what do you think is happening in the water below the surface? Is the water moving forward toward the shore?

To find out, you will need:

  • a small aquarium tank or clear container of similar shape and size
  • a cork
  • a small block of wood
  • masking tape

Fill the tank with water and place the cork in the center. Use the tape to mark the approximate location of the cork on each side of the container. At one end of the tank gently lower and raise a small wooden block in and out of the water to create waves.

How and where did the cork move? Energy in the form of waves move across the cork but the cork itself (and the water) moves in a circular motion. Try it!

A wave is a way in which energy travels from one place to another. There are many kinds of waves, such as water waves, sound waves, light waves, radio waves, microwaves and earthquake waves. All waves have some things in common.

The highest point the wave reaches is called the crest. The lowest point is called the trough. The distance from one crest to the next is the wave length. The number of waves that pass a given point in one second is the wave's frequency.

The crest, trough and wavelength of waves

When wind blows over the ocean's surface, it creates waves. Their size depends on how far, how fast and how long the wind blows. A brief, gentle breeze forms patches of tiny ripples on the surface called catspaws; strong, steady winds over long distances create large waves. But even when you feel no wind at all, you may encounter large swells created by distant storms.

In the open sea, waves make floating boats bob up and down instead of pushing them along. This is because the waves travel through water; they do not take the water with them. As a wave arrives it lifts water particles. These travel forward, then down and back so that each particle completes a circle. Circling movements of particles near the surface set off smaller circling movements below them.


Waves only seem to carry water with them; in fact each wave crest sets water particles circling.

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