Tuning fork uncertainty

[Heinsbergrelatz]

In a physics discussion when during lab times, we had to measure the speed of sound forming a standing waves in a long tube filled with water, by adjusting the height of the water in the tube. Now the frequency we produced was directly from a tuning fork, not some machine, so after we tap on to the tuning fork, we put it above the tube and listen to the loudest sound it produces.

 

My question is how on earth do you get the uncertainty values for the tuning fork or the frequency? i mean i know the other uncertainty values such as the wavelength etc... you can calculate them through the uncertainty of the height of the water column on the tube. But i have no idea how to find the uncertainty values for frequency because the range isnt given on the tuning fork, so how would i do this?

 

i will appreciate the help

[swansont]

If you were still in the lab you might be able to estimate it by comparing to a calibrated source or to other tuning forks, but I think you're doing this after the lab is done. In that case, you could estimate the machining error on the tuning fork and convert that into a frequency error, or you could ignore the error because it's small, and assume all the error is in the column height at which you had the loudest sound — that height range has to be significantly larger than the < 1Hz error you might have in a tuning fork. 1 Hz is most likely a few tenths of a percent, and added in quadrature to the height error isn't going to change the result much if the height error is at least several percent.

[Enthalpy]

The main uncertainty is what epoch and continent the tuning fork is meant for. A is 440Hz in some places, 444Hz in others, many instruments are built for 442Hz, it has been 435Hz for most of 20th century and was something like 415Hz during the Renaissance.

 

The proper way to determine that is to measure the fork with an electronic tuner. It will give you better than 0.5% precision.

 

Half a tone is 5.9% and electronic tuners often divide half tones in "cents". I hear 0.1% frequency difference under good conditions.

 

Other error sources are small: the initial precision of a tuning fork is of course better than 0.2% as compared to the intended frequency and the alloy used, elinvar, compensates the change in Young's modulus by its thermal expansion

http://www.nobelprize.org/nobel_prizes/physics/laureates/1920/guillaume-lecture.pdf p469:

36s per day or 0.04% between 0°C / 15°C / 30°C

 

Not bad, is it? This is one reason that makes music instruments difficult to build.

[Heinsbergrelatz]

Enthalpy: thank you for the reply but we dont have any electrical equaipments you have mentioned, so i guess manually is the answer.

 

Swansot: Im sorry i dont get your explanation, could you please clarify abit more in detail please? thank you

[tomgwyther]

Enthalpy: thank you for the reply but we dont have any electrical equaipments you have mentioned, so i guess manually is the answer

 

If you have access to a lap-top computer, try using AP tuner. It's very accurate and will allow you to measure frequencies in a lot of detail, including their exact pitch and harmonics

 

Its available here and it's free. I use it to tune piano's etc.

 

AP Tuner

[michel123456]

Now I know how to call a diapason in English.

[swansont]

Swansot: Im sorry i dont get your explanation, could you please clarify abit more in detail please? thank you

A tuning fork's frequency depends on its length. If you can estimate the precision to which one could make a tuning fork, you could estimate its frequency uncertainty.

 

Or you could ignore it since it should be very small, which you should be able to justify.