Every sound we hear, every photon of light that hits our eyes, the movement of grass blown by the wind, and the regular beat of the tides are all examples of waves. Waves are all around us.
But what makes a wave a wave? What characteristics, properties, and behaviors are shared by the phenomena that we characterize as being a wave?
Webster's dictionary defines a wave as, a disturbance or variation that transfers energy progressively from point to point in a medium. As Thomas Henderson elaborates, "a wave moves as the particles in the medium interact with the particles next to them" - as one particle is displaced from its equilibrium position, it exerts a push or pull on its nearest neighbors, causing them to be displaced from their equilibrium position.
But what does all this mean?
Have you ever "done the wave" as part of a large crowd at a concert or a baseball game? A group of people jump up, hands in the air and
then sit back down.
The people next to them see them and do the same and so on and so on until you have what looks like a wave travelling around the stadium.
In this case, the wave is: the people (particles) jumping up and sitting down (disturbance) travelling around the people packed stadium (medium).
Click to see the animation!
In science, a disturbance refers more specifically to a change or variation of pressure, electrical or magnetic intensity, electric potential, or temperature.
A medium is a substance or material through which a wave moves. It is a collection of interacting particles. In other words, the medium is composed of parts that are capable of interacting with each other. The interactions of one particle of the medium with the next adjacent particle allow the disturbance to travel through the medium.