Examples of waves

The following examples shows common transverse, compression and circular waveforms.
Transverse waves

Up-and-down motion creates transverse waves
Wave in ballgame

At the ballgame, someone in the stands may start up a "wave" by standing up and then sitting down. The people on one side then stand up and sit down, then the next people, and so one.

Everyone is still in their seats, but the wave traveled through the ballpark from one end to the other.
Rope or string

You can shake a rope, causing a wave motion. The parts of the rope only move up-and-down, but the wave moves from one end of the rope to the other. A guitar string also has this type of motion.

Vibrating string demonstrates waveform

Characteristics of waves

The characteristics of a waveform are wavelength, amplitude, velocity, and frequency. All periodic waveforms have these common characteristics.

There are special cases, where only one crest of the wave is seen, like the the wave at a ballgame or the sound caused by an impact or explosion. In those cases, there is still a wavelength, but there is no frequency, since the waveform is not periodic.
Wavelength

Wavelength is defined as the distance from one crest (or maximum of the wave) to the next crest or maximum.

Waveform showing wavelength and amplitude

Waveform showing wavelength and amplitude

The wavelength of an ocean wave is typically several meters. The wavelength of the electromagnetic wave used in a microwave oven is in the order of a centimeter.
Amplitude

The height of the wave is called its amplitude. Some areas consider the middle of the wave to its peak as the amplitude, while others consider peak-to-peak as the amplitude.

Amplitude relates to loudness in sound and brightness in light.
Velocity

The velocity of the wave is the measurement of how fast a crest is moving from a fixed point. For example, the velocity of water waves can be measured as their speed in a given direction with respect to the land.

The speed of sound is about 1000 feet/second. The speed of light is 186,000 miles/second.
Frequency

The frequency of waves is the rate the crests or peaks pass a given point. Frequency is the velocity divided by the wavelength designated as cycles (or peaks) per second. Cycles per second is also called Hertz.

Frequency = Velocity / Wavelength

Another way of writing that is:

Velocity = Wavelength x Frequency

Tip: A way to help remember equations is to look at their units of measurement. If Velocity is in meters/second, Wavelength is in meters and Frequency is in cycles/second, then the units of the equation would be:

meters/second = meters x cycles/second

The frequency is also the reciprocal of the time between crests passing a point or the period of the vibration. With this measurement:

F = 1/T
Summary

Waves are distortions in a material that may be transverse, compression or a combination of those movements. Light, sound and AC electric waves are important waveforms. The characteristics of a waveform are wavelength, amplitude, velocity, and frequency.







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