Students will use three simple toy instruments to explore fundamentals of sound and frequency in this inquiry exercise. Boomwhackers: Students will share a number of colored plastic tubes of various lengths. Standing sound waves are excited inside the tubes, with wavelengths a little longer than double the length of the tube. Twirling Pipes: When the sound pipes are twirled around, they produce a note whose pitch depends upon how fast you can twirl it! You can probably produce only three different pitches, or frequencies. The pipes are producing members of a harmonic series. Students will also make soda straw flutes.
The "Sound Sensor" required for this lab is readily available at your local music store as an instrument tuner with a built in microphone. Korg electronic tuners (about $20) make wonderful frequency meters! Each lab group would need one sound sensor.
Additional Equipment: Boomwhackers, Audioscope software or Sound Sensor for measuring frequency, Sound Pipe, Soda Straws, Scissors.
Acknowledgements: Thank you to Dr. J.R. Harkay author of Phenomenal Physics for providing this student inquiry activity. Adapted from "Pythagoras Sounds Off II: Wind Instruments," an Inquiry Exercise by J. R. Harkay. Seewww.PhenomenalPhysics.com for more information on the complete Guided Inquiry Curriculum.