How Are Mechanical Waves Produced?

Types of Wave

• There are three types of wave. Matter waves are the waves created by electrons and other subatomic particles. Electromagnetic waves are waves that do not need any kind of medium in order to transfer their energy, and can travel through a complete vacuum such as the space between the sun and Earth. Electromagnetic waves include light waves and radio waves. Mechanical waves can only travel through a physical medium such as water. The waves on the ocean are of this type.

Wave Pulses

• A mechanical wave is produced by a wave pulse, which is simply physical energy being transmitted across a medium. For example, there is a toy called a Newton's Cradle, consisting of a series of small metal balls hanging on strings from a small frame. If you cause the ball on the end to strike the ball next to it, it transfers the energy of the collision into the next ball in the form of a wave pulse. The energy travels through all of the balls until it reaches the other end, where it causes the last ball in line to swing out on its string. When the ball swings back, it sends a wave pulse back in the opposite direction.

How Wave Pulses are Produced

• Any kind of force or disturbance that affects a medium can cause the initial wave pulse that starts a wave. For example, if you hold a rope at one end and give it a jerk, the energy you create will travel down the rope as a wave. If you do it repeatedly, it creates a periodic wave, which is a wave pattern that repeats continuously. Even a "stadium wave," which is caused by fans in a stadium standing up and sitting down in sequence, works in exactly the same way. The first fan to stand up provides the wave pulse, which travels through the stadium audience as a mechanical wave.

Ocean Waves

• Ocean waves work the same way as other types of mechanical wave. The wind can start a wave pulse, which is the case with most of the waves on the ocean. Earthquakes can also start wave pulses, resulting in tsunamis. Tides are the result of a wave pulse started by the gravity of the moon. Even though waves can travel over vast distances across the ocean, the water does not actually travel at all. It is only the energy of the wave pulse that travels through the water, causing the water to rise and fall in a wave pattern.