Adjusting Air Column Length with Water: Why No Waves?

In summary, waves tend to reflect off different media with different impedances, such as air and water. While some sound may enter the water, most of it is reflected back into the air. In air column experiments, more energy is lost at the open end than at the closed end. It is believed that all waves lose energy when reflecting off objects, and the standing wave formed by boundaries can only be maintained by continuously providing amplitude to the incident wave to overcome this loss.
  • #1
atavistic
106
0
In many problems , to change the length of the air column we use water but I don't understand why waves don't pass into water and then the reflected wave will have less amplitude and hence standing waves could not be formed.
 
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  • #2
Waves tend to reflect off any interfaces between media, because the different media have a different "impedance." In this situation, you can think get away with thinking of impedance as simple resistance -- water is much harder to shake than is air.

- Warren
 
  • #3
Ye, but water will absorb also right?
 
  • #4
Yes, some of the sound will enter the water. If you're swimming underwater and a bomb goes off in the air above, you'll hear it! :smile:

But most of the sound is reflected back into the air.

In air column experiments like you describe, much more energy is lost at the open end of the column than at the closed (water) end. After all, some of the sound has to come out the open end so we can hear it.
 
  • #5
By the way I believe that there are no waves existing that reflect of an object without loosing any energy, particularly with soundwaves which loose their energy to the traverse wave, and to dispersion and heat. The standing wave induced by boundaries can only be maintained by continuously providing amplitude to the insident wave, so the loss can be overcome.
 

1. How does adjusting the air column length affect the presence of waves?

Adjusting the air column length does not have a direct impact on the presence of waves. Waves are created by disturbances in the medium, in this case air, and not by the length of the column itself.

2. Why do we use water when adjusting the air column length?

Water is used to adjust the air column length because it is denser than air and thus provides a more stable medium for the waves to travel through. This allows for more accurate measurements and observations.

3. Is there a specific water level that needs to be maintained when adjusting the air column length?

Yes, the water level should be kept at a consistent height throughout the experiment to ensure consistent results. Any changes in water level can affect the behavior of the waves.

4. Can adjusting the air column length affect the speed of the waves?

No, the speed of the waves is determined by the properties of the medium, in this case air, and is not affected by the length of the column. However, the length of the column can affect the wavelength and frequency of the waves.

5. How can adjusting the air column length be used to study wave behavior?

By adjusting the air column length, we can observe changes in wavelength and frequency, which can help us understand the relationship between these properties and how they affect wave behavior. This can also be used to study other wave phenomena, such as interference and resonance.

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