Name__________________________
Date________________
Period _________
Standing Waves in Open and Closed Pipe Resonators
Many musical instruments depend on the musician in some way moving air through
the instrument. This includes brass and woodwind instruments, as well as instruments
like pipe organs. All instruments can be divided into two categories, open ended or closed
ended. A “pipe” can be any tube, even if it has been bent into different shapes or has holes
cut into it.
An open ended instrument has both ends open to the air. An example would be an
instrument like a trumpet. You blow in through one end and the sound comes out the other
end of the pipe. The keys on the trumpet allow the air to move through the “pipe” in
different ways so that different notes can be played. Open ended instruments have the
antinode present at the end of each pipe. This means that lowest fundamental frequency
occurs when there is one half a wavelength in the pipe.
A closed ended instrument has one end closed off, and the other end open. An
example would an instrument like some organ pipes (although in some designs they are
open), or a flute. Although you blow in through the mouth piece of a flute, the opening you
are blowing into isn’t at the end of the pipe, its along the side of the flute. The end of the
pipe is closed off near the mouth piece. Closed ended instruments have a node present at
the closed end and an antinode present at the open end. This means that lowest
fundamental frequency occurs when the length of the pipe is one quarter wavelength.
Materials – Physics Aviary website listed in the procedure
Procedure
1. Open the following website:
a. https://www.thephysicsaviary.com/Physics/Programs/Labs/ResonanceTubeLa
b/index.html
2. Once the site opens click “Begin”.
3. Click “Activate Grid”, this will bring up a ruler on top of the pipe.
4. Record the length of the pipe in each part of the data table.
a. The lengths will be the same for when the cap is on or off.
5. Click the pipe fours and record the length after each click.
6. Using the formulas for open and closed pipe resonators, fill in the Predicted
Frequency column of the data chart.
a. The speed of sound is 345 m/s.
i. Using the formula to determine the speed of sound, fill in the
temperature blank.
7. Click the pipe one more time, this will bring it back to its original length.
8. If the predicted frequency for the length is greater than 250 Hz, then flip Range
Selection the switch to 250 Hz – 1000 Hz. If not, then leave the switch alone.
9. Press “Scan” and wait to see the actually frequency.
10. Record this value in to the Actual Frequency column of the data chart.
11. Click the pipe four times and follow steps 8-10 for each length.
12. Now click Remove Cap, and perform steps 8-11 for the Open Pipe Resonator data
chart.
13. Calculate the percent error.
a. The accepted value is the frequency from the simulation.
14. Move on to the Analysis Questions that are posted as an assignment in Google
Classroom.
Data Charts
Temperature of Air in the simulation ___________________________
Closed Pipe Resonator
Length of Pipe (m)
Predicted Frequency
(Hz)
Actual Frequency
(Hz)
Percent Error (%)
Calculations for Closed Pipe Resonator
Open Pipe Resonator
Length of Pipe (m)
Predicted Frequency
(Hz)
Actual Frequency
(Hz)
Calculations for Closed Open Resonator
Percent Error (%)