What Is The Period Of A Wave?

Question

Waves are extremely important phenomena in physics. In nature, vibrations are found everywhere.

From the swaying of atoms to the large swings of sea waves, we find examples of vibrations in almost every physical system.

A wave can be defined as a periodic or regularly recurring disturbance that carries energy from one place to another.

What Is The Period Of A Wave?

The period of a wave is the measure of time it takes for the wave cycle to complete.

We usually measure the wave period in seconds and represent it with the letter T.

Just like all waves, it has crests or peaks, which are the highest points.

It also has troughs, the lowest points. The length of a wave is the distance between one of its peaks and the next peak.

Wavelength is represented by the Greek letter lambda λ.

The distance between peaks is equal to the distance between troughs.

We can also measure the wavelength from one trough to another.

In either case, the wavelength will measure the distance of one wave cycle, or one completion of a repeating wave up and down.

Before finding the period of a wave, it is useful to know its frequency, i.e. the number of repetitions of the wave cycle in a given time period.

In this graph we see five different waves with different frequencies.

You can see that a different number of cycles occur in the same time period.

You can determine the exact number by counting the peaks or troughs.

The red wave has the lowest frequency among the five because it has the least number of repeating cycles, and the pink wave has the highest frequency because it has the most repeating cycles.

The frequency (f), can be obtained by dividing the speed of the wave, usually symbolized by the letter v, by the wavelength.

Remember that we represent it with the Greek symbol: lambda λ.

We usually measure the wavelength in meters and the velocity in meters per second. The frequency found with these units will be measured in Hz (hertz), another way of saying cycles per second.

The wave period is just the reciprocal of the frequency, which means that any wave will have a wave period of 1 over the wave’s frequency.

The standard unit for period is in seconds, abbreviated as the letter S.

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