# Homework Help: Which harmonics would be observed on an electric guitar?

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1. Dec 1, 2017

### thomas19981

1. The problem statement, all variables and given/known data
The electric guitar radiates very little sound directly, but instead relies upon pick-ups (transducers) placed beneath the strings. Establish, showing clearly how you reach your answer, which harmonics of the open string you are likely to observe if the pick-ups are placed.
1)close to the bridge of the guitar.
2)around the mid-point of the strings
3)a quarter of the way from the bridge to the nut
4)$98 mm$ from the bridge, when the length of the open string is $648 mm$
2. Relevant equations
$n\lambda/2=L$

3. The attempt at a solution
I'm not totally sure what to do for all the above parts but I've derived the equation above to help me get the number of the harmonic I would observe. At a guess i'd say that the transducers give nodes so from that I can deduce n which would give me the number of the harmonic. Is that the right idea or am I totally wrong?

2. Dec 1, 2017

### BvU

You may want to reconsider that (see here)
When in doubt, make sketches

3. Dec 4, 2017

### PeterO

The pick-up works when the string just above it is moving.
Sketch the modes of vibration of a string, and check whether there will be a node (the string not moving) where the pick-up is.
Note: You said "At a guess i'd say that the transducers give nodes". On the contrary, the transducer will only detect/produce sound where there isn't a node.

4. Apr 2, 2018

### sophiecentaur

After you have decided on the motion of the string, you should consider the fact that the signal produced by a guitar pickup is due to variable reluctance of the magnetic circuit containing the head and the steel string. This will introduce a large second harmonic component of the periodic motion of the string.