Physics of GuitarsBy: The Chads

Brief History of Guitars•Modern guitars can be traced back to

Spain; derived from the Spanish word “Guitarra.”

•Romans introduced “cithara”; made from wood, connected by ribs, with a tuning bar and strings.

•This was eventually combined with another instrument called the Oud, a sort of early bass guitar, to create an early predecessor of the modern guitar.

Physics of Acoustic Guitars•Acoustic guitars consist of four key

components: the body, strings, neck, and sound hole or “air cavity.”

•Each individual part contributes to the unique sound of acoustic guitars.

•The body has two plates; the top plate resonates high pitches while the back plate resonates low pitches.

Acoustic Guitars cont.• The sound waves resonate from the strings and

are transferred in to the body through the bridge.

• The waves bounce around inside the guitar affecting the air, thus creating the sound we hear coming from the sound hole.

• You can acquire higher pitches by holding down the string on lower frets, while you get the inverse result on higher frets. This sound is determined by tension on the string while held down on the neck.

Sound wave resonance patternshttp://ffden-2.phys.uaf.edu/211.web.stuff/billington/interference.gif

Front plate of the guitarhttp://ffden-2.phys.uaf.edu/211.web.stuff/billington/gibson.gif

Acoustic Guitars

Acoustic Guitars

Several Alvarez acoustic guitarshttp://www.warpdrivemusic.com/images/ben/alvarez/Alvarez_Mastershot.jpg

Physics of Electric Guitars•Electric guitars also have crucial components

including the pickups, strings, and the body.•Electric guitars have electromagnetic pickups

that have a coil of wire wrapped around them.•The close distance between the strings and

pickups make the magnets create north/south poles on the strings.

•Playing a string changes the magnetic field around the pickup and get transmitted through the wires to the amp.

Electric Guitars cont.• String vibrations can be calculated according to

basic physics laws including relationships between vel., wavelength, and frequency and equations describing motion of strings fixed at both ends.

• All the strings use the same range of wavelengths; to make diff. frequencies (pitches), velocity must vary.

• Velocity can vary by changing mass density and/or tension of strings.

• It’s preferred to play guitar with uniform tension on all strings.

Electric GuitarsWaves/vibrations with bar magnet

Waves/vibrations with individual magnets

Electric Guitars

Electric Guitarshttp://orgs.usd.edu/nmm/Tours/GalleryViews/EveristGallery/ElectricGuitarsDisplay2.jpg

The Actual Physics•D=l/1.0595^n

▫ D = distance from neck, l = length of string, n = number of fret starting with 1

•V=fλ▫V = velocity of the wave, f = frequency,

lambda (λ) = wavelength•V=T/u

▫Wave depends on 2 factors: T = tension and u = mass density of the string

GET AT ME.THE CHADS OUT

Work Cited• http://ffden-2.phys.uaf.edu/211.web.stuff/billington/main.htm• http://www.associatedcontent.com/article/372599/how_it_all_began_the_origin_of_the.html?cat=33• http://ffden-2.phys.uaf.edu/211_fall2004.web.dir/Jeremy_Bloomstrom/physics.htm• http://www.fingerpick.com/pickups.htm• http://www.blueshawk.info/how_pickups_work.htm