War of the Waves by Carly Altizer

Carly Altizer

Natural

War of the Waves

 

This photograph of water striders demonstrates surface tension and wave interference. A water strider is small enough that surface tension, which is the attractive force between molecules of a liquid, is able to keep it from sinking. Water molecules are attracted to each because of their polarity. The two hydrogen atoms of a water molecule have a partial positive charge, and the oxygen atom has a partial negative charge. Since opposite charges attract, the hydrogen atoms of one water molecule are drawn to the oxygen atom of a neighboring water molecule, and this attraction creates a hydrogen bond. The combined effect of the hydrogen bonds among the water molecules creates surface tension. Wave interference also occurs when male water striders vibrate their legs to create ripples in the water. The waves that are the farthest away from the water strider on the left demonstrate constructive interference. Constructive interference occurs when the top of one wave, which is the crest, meets the crest of an adjacent wave. Likewise, constructive interference also happens when the bottom of a wave, or the trough, meets the trough of an adjacent wave. Waves that experience constructive interference combine to create a larger wave. On the other hand, destructive interference occurs when the crest of one wave hits the trough of another wave. Waves that meet in this manner are out of phase, and they cancel each other out. Multiple examples of destructive interference can be seen in this photograph. The two sets of waves produced by each water strider meet in the center of the photograph and cancel each other out. Also, notice the smaller wave patterns produced by the water strider on the left. They meet out of the phase and interfere destructively at the points where they intersect.

 

 

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