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Randy Barnes’ School of Rock Science Project Homemade Guitars

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Tuesday January 31, 2012

By Marcie Bolton

When I asked Middlebury Union Middle School science teacher for a synopsis of his current guitar project, he gave me an in-depth look into an interesting eighth grade science lesson.  Mr. Barnes explains, “The project was given as part of our study of electromagnetism in conjunction with the over-arching theme of the law of conservation of energy.  More specifically, students need to utilize the concept of electromagnetic induction in order to convert the sound from the strings when they strum to an electric current, which is then sent into the amplifier where it's converted back into sound (only louder, hence the amplifier of course).  The key to converting the vibrations of the string into current is the pick-up.  The pick-up is essentially a tiny generator, where kinetic energy (the string moving) is converted into electrical energy.  A current is generated when a magnetic field is cut through by a coil of (usually) copper wire.  In the pick-up, the magnet is placed inside a little bobbin that has enamel-coated copper wire wound around it.  When the string is vibrated a couple of millimeters above the magnet, the magnetic field of the magnet wobbles (which, effectively, is the magnet moving in relation to the coil).  This wobbling magnetic field "pushes" the electrons in the copper coil.  These moving electrons are electrical current.  That current flows out of the guitar through the jack, into the amplifier.  That's the project in a nutshell.”  Some of the students started in on the project right away and completed it early.  Shauna Ralston, an eighth grader, said her father had to travel to Essex Junction, Vermont to find magnet wire due to it being on backorder in the Middlebury area.  Faith Isham was able to share some extra wire of Shaunas, and decided to get right to business as well, finishing with time to spare.  Felicia Baslow, in addition to hearing the class lecture, watched a video on how to make the guitar and then completed her project.  The kids seemed genuinely excited about the project. Keep up the good work!  

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