# An experiment to determine the speed of sound using a closed pipe.

• _Mayday_
In summary: I am not sure what your setup is exactly. I was assuming that you could vary the level of the water and look for resonance. This is the way I have seen it... well, that and a ruler! :smile:

#### _Mayday_

Would it be possible for someone to check over my experiment? I have not conducted the experiment yet, but I would like to make sure I am on the right tracks.

The equation I will be using to determine the speed of sound is:

$$v=f\lambda$$

$$v$$ is the speed of sound

$$f$$ is the frequency and this will be known

$$\lambda$$ is the wavelength, this is what I must find

I will have a large cylinder fulled with water and inside it there will be a moveable tube. Correct me if I am wrong, but am I measuring from the top of the tube to the water? How do I use this to determine the wavelength? There must be an equation that relates the distance from the top of the pipe and the surface of the water. As this experiment involves a close pipe so I think I have the equation for the length of the pipe.

$$Length=\frac{1}{4}\lambda$$

My question is, is this length the length of the moveable pipe? If so I can measure that and then calculate the wavelength, though this length may be the point at which I get a resonance.

Any help would be great, thanks!

Bit Confused :yuck:

_Mayday_

I'm not entirely sure of your set up from your description but normally one would use the length of the pipe.

What I will do is draw it all up on paint and then host it, that should make things easier to understand

_Mayday_ said:
Would it be possible for someone to check over my experiment? I have not conducted the experiment yet, but I would like to make sure I am on the right tracks.

The equation I will be using to determine the speed of sound is:

$$v=f\lambda$$

$$v$$ is the speed of sound

$$f$$ is the frequency and this will be known

$$\lambda$$ is the wavelength, this is what I must find

I will have a large cylinder fulled with water and inside it there will be a moveable tube. Correct me if I am wrong, but am I measuring from the top of the tube to the water? How do I use this to determine the wavelength? There must be an equation that relates the distance from the top of the pipe and the surface of the water. As this experiment involves a close pipe so I think I have the equation for the length of the pipe.

$$Length=\frac{1}{4}\lambda$$

My question is, is this length the length of the moveable pipe? If so I can measure that and then calculate the wavelength, though this length may be the point at which I get a resonance.

Any help would be great, thanks!

Bit Confused :yuck:

_Mayday_

This equation is (approximately) correct if L is the length of the air column , i.e. the air section going from the water to the rim of the tube AND if this is the smallest distance producing resonance. This is where the sound wave is present.

But in a real experiment, the antinode is not exactly at the rim of the tube so this does not give very good results. It's preferable to change the water level and locate two adjacent resonance points. In that case, you may use that the distance between two adjacent resonance points is lambda/2.

kdv said:
This equation is (approximately) correct if L is the length of the air column , i.e. the air section going from the water to the rim of the tube AND if this is the smallest distance producing resonance. This is where the sound wave is present.

But in a real experiment, the antinode is not exactly at the rim of the tube so this does not give very good results. It's preferable to change the water level and locate two adjacent resonance points. In that case, you may use that the distance between two adjacent resonance points is lambda/2.

Can you please expand on that? I am not sure what you mean by two adjacent resonance points? How would I go about finding those? It would be a nice bit of extra work I could pop in for some extra marks

Thanks for the response. Kurdt I don't think I will draw that out after all as I have an answer, thanks for your time though!

_Mayday_ said:
Can you please expand on that? I am not sure what you mean by two adjacent resonance points? How would I go about finding those? It would be a nice bit of extra work I could pop in for some extra marks

Thanks for the response. Kurdt I don't think I will draw that out after all as I have an answer, thanks for your time though!

well, I am not sure what your setup is exactly. I was assuming that you could vary the level of the water and look for resonance. This is the way I have seen it done: there is a source of sound at a fixed frequency near the opening of the pipe and the water level is varied while one searches for resonances. What is yoru setup? Another possibility would be to keep the water level fix and vary th efrequency in which case one should look for resonances at two adjacent frequencies and there is a formula for that as well

I have a big tube filled with water, the water level will not change. I then have a hollow perspex tube which I vary the distance up and down on the inside of the water filled tube. I have varied frequency forks that are a fixed distance from the top of the perspex tube. i want to know how I go about calculating the wavelength.

Thans for you help =]

## 1. How do you set up the experiment to determine the speed of sound using a closed pipe?

The experiment can be set up by attaching a speaker to one end of the closed pipe and a microphone to the other end. The pipe should be completely sealed, with no air leaks, and filled with a known gas. The distance between the speaker and microphone should be measured and recorded.

## 2. What is the purpose of using a closed pipe in this experiment?

A closed pipe allows for the sound waves to travel back and forth between the speaker and microphone, creating a standing wave. This helps to accurately measure the speed of sound in the pipe.

## 3. How is the speed of sound calculated in this experiment?

The speed of sound can be calculated by dividing the distance between the speaker and microphone by the time it takes for the sound wave to travel back and forth between the two points. This time can be measured by using a stopwatch or a computer program.

## 4. How can the speed of sound experiment be improved for more accurate results?

The experiment can be improved by using multiple trials and taking the average of the results. This helps to account for any errors or inconsistencies in the measurements. Additionally, the experiment can be repeated using different gases to see if there is any variation in the speed of sound.

## 5. What are some potential sources of error in this experiment?

Some potential sources of error in this experiment include air leaks in the closed pipe, human error in measuring the distance and time, and variations in the gas used. It is important to ensure that the equipment is set up correctly and to take multiple measurements to minimize these errors.