Progressive waves are like energy transfers that move from one place to another. They're different from stationary waves because they actually progress or on the material that carries them. The wave's crests and troughs move back and forth, creating the movement of the wave from one place to another. You can imagine this movement as the wave traveling from point A to point B. When the wave reaches its highest point, that's called the crest. And when it gets to the lowest point, that's the trough. Progressive waves are pretty cool, huh?

Examples of progressive waves

Have you ever noticed how waves move through space? They're actually called progressive waves and they happen when an object oscillates and produces waves that travel through a medium like a liquid, gas, solid, or even a vacuum. For example, when the wind blows across the ocean, it generates waves that move through the water. Or, when you hear sound, it's actually waves moving through the air. Even in the ground after an earthquake, there are waves moving through the solid earth. And believe it or not, waves can even move through a vacuum, like the light that comes from the sun. The sea is a great example of a medium that propagates many different types of waves, including electromagnetic waves, seismic waves, wind waves, and sound waves. It's pretty amazing how many different types of waves can be found in one place!

The properties of progressive waves

As progressive waves move from one point to another, undulations will repeat if the waves are being produced constantly. The four main characteristics of a progressive wave are its wavelength, period, frequency, and velocity.

The wavelength of progressive waves

This is defined as the length from the beginning to the end of the wave.

The wavelength of a progressive wave is related to its energy. The amount of energy differs depending on the nature of the wave. In ocean waves, smaller wavelengths indicate waves with low energy, while in electromagnetic waves, shorter wavelengths indicate larger energies.

The period of progressive waves

As waves move from one point to another, the pattern will repeat if the oscillation does not change. The time it takes for the pattern of oscillation to pass through one point is called the period, which is better defined as the time between two crests or troughs. It is measured in seconds.

Figure 3. The time it takes for a wave to move between the points that mark its beginning and end (green dots) is the wave period.

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The velocity of progressive waves

If we divide the wavelength by the wave period, we get the time it takes for the wave to advance. This is the wave velocity, which is measured in m/s.

The frequency of progressive waves

The inverse of the wave period tells us how long it takes for the wave to repeat itself in one second. If the frequency is 1, it takes 1 second for the wave to repeat itself. If it is lower than 1, the wave is faster. If it is greater than 1, the wave is slower. The frequency is the inverse of the period, and it is measured in Hertz.

The cycle of progressive waves

When we talk about progressive waves, we often refer to the complete pattern of the wave from crest to trough as a wave cycle. The speed of the wave is connected to both its frequency and velocity. But how do we actually measure these properties? Well, we need a reference point. In order to measure the wavelength and wave height, we need reference points on both the horizontal and vertical axes. And to measure the properties related to wave cycles, we need to take the time it takes for the wave to move from one point to another. With these measurements, we can better understand the properties of progressive waves and how they behave in different mediums.

Measuring the wavelength and wave height

To measure the wavelength, we need to fix a point on the horizontal axis. To simplify this, we can take a crest, which is easiest to identify (as we said earlier, the crest and trough represent the wave’s maximum and minimum heights). Measuring the distance between two consecutive maximums, we get the wavelength.

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To measure the wave height, we need to measure the distance between the crest and trough, as shown below.

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Half the distance between the crest and the trough gives us the wave amplitude.

Measuring the wave period and frequency

To measure properties related to the wave cycle, we need to measure the time it takes for the wave to move from one point to another. Again, we need to select a fixed point, with the crest or trough being the best options.

If we measure the time it takes from one crest or trough to the next, we obtain the wave period.

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In summary, progressive waves are waves that move from one position to another. They have various properties such as wavelength, height, amplitude, velocity, frequency, and period. These waves can be found in different mediums, such as sound waves in the air, seismic waves in the ground, and ocean waves in the water. The dimensions of the wave can affect certain properties, such as wave height, amplitude, and wavelength. On the other hand, properties like wave period, velocity, and frequency are dependent on the time it takes for the wave to complete one cycle. Understanding the properties of progressive waves is crucial in many fields, including physics, engineering, and oceanography, among others.

Progressive Waves

What is a progressive wave?

A progressive wave is a wave that moves from one point to another.

What is the difference between a progressive and a stationary wave?

Progressive waves move from one point to another whereas stationary waves do not. Respective examples are ocean waves (progressive) and the vibrations of a guitar string (stationary).

How do we measure the wavelength and wave period?

To measure the wavelength, we need to measure the distance between two consecutive maximums (crests).By measuring the time it takes from one crest to the next, we obtain the wave period.

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