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Rockin' the World... With Physics From its creation, the electric guitar has been the essence of rock music. It is often not thought of how the guitar actually works and the physics behind it. It's incredible how popular and perfected the guitar has become from what it originally was, but yet constantly overlooked as an amazing musical instrument. From coast to coast, nation to nation, the electric guitar still rocks the world today.

By the 20th century, engineers, makers, and musicians began to formulate ways of electronic amplification. In 1931, George Beauchamp, with the help of Adolph Rickenbacker, produced an "electromagnetic pickup in which a current passed through a coil of wire wrapped around a magnet, creating a field which amplified the strings' vibrations." Gibson was a vital electric guitar producer, while Fender formed the "Fender Electric Instrument Company." The Broadcaster was created by Fender, which was more "concerned with utility and practicality rather then looks". Because so many guitars were made of only wood, most makers and players did not consider the electric guitar a "true" instrument. In the 1940's, a guitarist named Les Paul "mounted strings and pickups on a solid block of pine to minimize body vibrations." Thus, he created the "log" guitar. For a while, only jazz musicians such as Charlie Christian and country musicians declared that the electric guitar would make an "authentic" sound. As more and more jazz players were picking up the electric guitar, it started to attract a sound that caught audiences' ears.

Throughout the years, the electric guitar has been played by many greats, such as Jimi Hendrix, Eric Clapton, Slash, and David Gilmour to name a few. But how do they get their tone? It all comes down to physics. When an electric guitar string is strummed, the vibration of the strings are picked up by a pickup. The pickup on the guitar is a an electromagnet wrapped with wire (smaller than a human hair) over 7,000 times !!!!

{A pickup without its pickup cover. Note the wire wrapped around the magnets. A diagram showing where the pickups and other parts of a guitar are located.}

The pickup creates a stable magnetic field around itself. Once the string is strummed, the field is interrupted. As the string vibrates back and forth, it creates an electric current that is routed to an amplifier, intensifying the sound. The string almost acts as a generator for the guitar, generating electricity with the vibration between the metal string and magnetic pickup. All pickups are basically electromagnets that "pick up" vibrations of the string and turn them into electric current.



{This diagram shows how the electromagnet creates a magnetic field around itself. When the vibration occurs, the magnet picks up the vibrations and uses magnets to create power. The current is sent from the coil of wires to the amplifier where they can be heard.}

Basically, in physics we have learned how to run an electric current through a solenoid to create a magnetic field. We tested this in the lab where we used the magneprobe. However, with an electric guitar, this operation is done backwards. As was stated earlier, the vibration in the strings disrupts the magnetic field created by the permanent magnets embedded in the pickup, and therefore an electric current matching the vibration of the strings is formed in the coil of wires around the pickup. This process can be seen in the diagram above. After the current is created, it is fed through a **circuit** that is shown in the diagram below. The current is run from the pickup coil through each resistor, and each of these resistors adjust and modify the electrical signal so in the end it produces the desired sound.



{This is a diagram of the circuit the current runs through before reaching the jack, which leads to the amplifier. The **volume** and **tone** resistors adjust those aspects of the sound by affecting the current in certain ways.}

{This diagram also shows how the metal strings disrupt the magnetic field around the pickup, creating the electric current.}

Typically, guitars are tuned to a frequency of 440 hertz. When a string is played, the vibration interacts with the pickups, vibrating at 440 cycles per second, or Hz. This is how the string and pickup interaction works. Ahh, music to my ears.

To sum everything up, electric guitars use magnets to create a magnetic field around the pickups. This magnetic field is disrupted by the strumming of the metallic string above the given part of the pickup. This vibration in the field creates the electric current which is ultimately sent to the amplifier, which puts it through a speaker. Who would have known that the most important part of an electric guitar involved magnetism and physics?

Still a little confused? Don't worry, maybe this video will help.

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WORKS CITED: "The History of the Electric Solid Body Guitar ." // The History of Rock and Roll //. Web. 17 Mar. 2011. . "Invention of the Electric Guitar :: Smithsonian Lemelson Center." Web. 17 Mar. 2011. []

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