Frequencies of fundamental standing waves

In summary, the conversation discusses a question about closed-end air columns and the relationship between length and wavelength for harmonics. The answer is determined to be (A) f_1, with the reasoning that an increase in length will produce an increase in wavelength. However, it is clarified that the speed of sound in air and water is the same regardless of the length of the medium. The explanation is deemed unclear and it is suggested to rewrite it for better understanding.
  • #1
ardour

Homework Statement


upload_2017-10-3_20-50-29.png


Homework Equations


Harmonics equations

The Attempt at a Solution


So, I got (A), which is the answer key is correct, but I'm not sure whether my reasoning is right or not. Would this be considered a closed-end air column question? Anyways, according to the length-wavelength relationships for the harmonics (which can be seen here: http://www.physicsclassroom.com/class/sound/Lesson-5/Closed-End-Air-Columns), an increase
in length will produce an increase in wavelength. Since both columns have the same height of water in them, the speed of sound through both should be the same, right? This means that the taller column will have a lower frequency than the shorter column, which will need a higher frequency to compensate for the shorter height, making the answer (A) f_1. Is my reasoning correct?
 
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  • #2
ardour said:
Since both columns have the same height of water in them, the speed of sound through both should be the same, right?
That's not the reason. The speed of sound in air as well as in water is the same regardless of the length of the medium in which it travels. These are simply two pipes with one end closed having different lengths.
 
  • #3
Ok, I understand. Given the rest of the explanation though, is it correct?
 
  • #4
Your explanation is not clear, but you are on the right track. However, the statement
ardour said:
Since both columns have the same height of water in them, the speed of sound through both should be the same, right?
implies that if the the height of water is different, the speed of sound will be different. Why should the speed of sound depend on the height of the water column? Try rewriting your explanation to make it more clear. Doing that will help you clarify your ideas in your mind.
 

What are frequencies of fundamental standing waves?

Frequencies of fundamental standing waves refer to the natural resonant frequencies at which a standing wave can form on a medium, such as a string or air column.

How are frequencies of fundamental standing waves calculated?

The frequencies of fundamental standing waves can be calculated using the formula f = n(v/2L), where f is the frequency, n is the harmonic number, v is the speed of the wave, and L is the length of the medium.

What factors affect the frequencies of fundamental standing waves?

The frequencies of fundamental standing waves are affected by the length, tension, and density of the medium. The type of medium and the boundary conditions also play a role in determining the frequencies.

What is the relationship between frequencies of fundamental standing waves and harmonics?

The frequencies of fundamental standing waves are directly related to the harmonics of the medium. The first harmonic, or fundamental frequency, is the lowest frequency at which a standing wave can form, and each subsequent harmonic is a multiple of the fundamental frequency.

Why are frequencies of fundamental standing waves important?

Frequencies of fundamental standing waves are important in understanding the behavior of waves and how they interact with different mediums. They are also essential in the fields of music, acoustics, and engineering, where they are used to design and tune instruments and systems.

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