Resonance Tube
Resonance Tube
Date performed: 5/27/2021
Date due: 6/1/2021 1PM
Download phyphox!!
Background
Air generates tone where an antinode is located
Resonance occurs when standing waves form
Harmonic waves formed from sound- fundamental frequency (n=1) as lowest (f1)
Second harmonic- first overtone with tripe frequency as f1
Use figure 17.29 on first page of pdf for reference to relationships between length, frequency, and wavelength in a closed tube when producing standing waves and resonance
Procedure
Measure room temperature
Measure and cut straws to required lengths in cm in table
Test blowing over top while blocking other end
Phyphox app- select “Audio Spectrum”
Use “Pan and Zoom” to locate first and second peaks in sound waves
Continue filling out rest of table
Table to fill out and include in “Data”
Length of Straw (m) f1 (Hz) f3 (Hz) (m) (m^-1)
“Data analysis questions”
Before leaving lab, submit (ALSO INCLUDE IN REPORT):
Completed data table
Screenshot selecting f1 and screenshot selecting f2
Plot graph f1 vs. 1/wavelength in excel with trendline equation (include as response to #8 for data analysis and uncertainty in your report)
Questions for report: #6-11 in a separate section, #10/11 instead of comparing data with other students, do some research on the relationship of temperature to speed of waves
University of Hartford PHY113-PHY121 Fall 2020
Resonance Tube
Purpose
The physics principle behind tube instruments such as flute and harmonica is sound resonance in tubes.
The object of this experiment is to determine the frequencies of the sound and the conditions for
esonance using tubes with different lengths.
Equipment
Straws, scissors. Phone APP: Phyphox. Excel.
Note: If you can’t find straws, you can disassemble your pen for a tube and block one end at different
positions for different lengths. If you don’t have a smart phone, you can download and use Audition on
your desktop or laptop. (It is free for 7 days.)
Theoretical background
Many mechanical systems have normal modes of oscillation. These include columns of air (as in an
organ pipe) and stretched strings. When air is blowing along the edge of pipes, air generates an edge
tone where the antinode is. The resonance happens as standing waves are formed in the tube because
of air compression.
Here is the diagram of closed tubes that we are investigated in this experiment. All sounds consist of
different harmonic waves. The one with the lowest frequency is called fundamental frequency ??1; the
second harmonic is the first over tone with the triple frequency as ??1; the same further ones are with
5??1, 7??1 … The Fourier transform is a tool that can split the sound into harmonic waves with different
frequencies.
From College Physics OP, Chapter 17 Physics of Hearing, Page 669.
The basic wave relation for all simple waves is
?? = ????
where ?? is the velocity of the wave, ?? is the frequency, and ?? is the wavelength.
In the case of sound waves in air, at sea level, the velocity (in m/s) is estimated by the following
expression
?? = XXXXXXXXXX??
University of Hartford PHY113-PHY121 Fall 2020
where ?? is the air temperature in degrees Celsius.
Experimental Procedure
1. Measure and record the temperature of the air in the room.
2. Measure and cut straws into different lengths.
3. Test: blow over the top of the tube on one end while using a finger to block the other end. You
should be able to hear a sharp sound. If you have difficulties producing a sound, the following
video can help you complete this experiment.
Resonance Tube Help Video
4. Use Phyphox App, Audio Spectrum function to record the fundamental frequency (the first
strongest peak) and the first overtone frequency (the second strongest peak) of its sound. “Pan
and Zoom” can help to zoom the area that you want to focus on; “pick data” can help to locate a
specific point and read the frequencies.
5. Repeat step 2-4 to fill out the following table.
L (cm) L (m) ??1 (Hz) ??3 (Hz) ?? = 4?? (m) 1/?? (m−1)
15
12
10
9
Fundamental frequency
First overtone frequency
https:
ensemble.hartford.edu/Watch/Jw3j7YPy
University of Hartford PHY113-PHY121 Fall 2020
8
7.5
Data analysis and uncertainty
6. Question: How does fundamental frequency change with the lengths of straws?
7. Question: Based on your data, what is the relationship between the data in column ??1and ??3?
8. Copy the data of column ??1 and 1/?? to excel, make a plot and use a linear equation to fit the
data.
9. Record the slope of plot. It is the speed of sound at your temperature in m/s.
10. Compare your data with other students with different temperature.
11. Question: With temperature increases, how does the speed of sound change?
Purpose
Equipment
Theoretical background
Experimental Procedure
Data analysis and uncertainty