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The Soda Bottle Speaker-Introduction
Build your own speaker with a magnet, some fine wire, a little hot glue, paper and a plastic bottle. This page describes the construction of the "Soda Bottle Speaker" and also provides a few suggested experiments.
The Soda Bottle speaker was originally developed as a simple, low cost, and fun laboratory experiment, suitable for introductory physics classes. Students enjoy building a working device that they can take home with them and show their friends. We first used the experiment as part of the "Acoustical Foundations of Music" (Phy 103) at Mercer University. Speakers are simple to build and are suitable for high school physics classes as well. Students in lower grades can build them, but the instructors might have to pre-make a few of the tricky parts.
The experiment can be used at a number of different levels. Simply building a working speaker is exciting and interesting. More advanced classes can measure the sound level produced as a function of frequency and study resonance. The speaker can be used as a transducer to drive mechanical devices and springs. In an electronics class, the speaker is useful for illustrating reactance and impedance. Bottles of different sizes can be used to build woofers tweeters. A dynamic microphone is nothing more than a speaker working in "reverse". Of course, some of these more advanced equipment. What ever the level of student, there is just something amazing about making a crude looking device that can play music.