Tuning Fork Experiment (TBR Physics CH6)

[Lunasly]

Reference: TBR Physics Chapter 6; Passage IV; #22.

This is your typical tuning fork experiment you do in first year physics. It basically a pipe closed at one end and you produce a resonance by holding a tuning fork over a tube filled with water to some given height.

Q. What is the wavelength of sound produced by the tuning fork in trial #3.

Trial #3 data:
Frequency (Hz) = 680
Length (to plug into proper equation) = 12.5 cm (can keep in cm because answers are in cm).

Answer: 50 cm

This isn't a difficult question had the author not assumed that 680 Hz was the fundamental frequency. I immediately went to the function wavelength = 4L/n. I plugged in n = 5 because I assumed that trial 3 of the 5 trials would be n = 5 given that n can only be an odd number in this experiment (we are dealing with a closed pipe).

Why did the author assume that n = 1?

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[BerkReviewTeach]

There's a caveat at the end of the paragraph stating that the students measure the fundamental mode. So, assuming the frequency for each tuning fork is its fundamental and given that the data in the table is from the fundamental measurement the students found, the solution bases it on n=1.

 

[Lunasly]

Thanks BRT