== Applications == 

 A friend and I are both guitarists and we've been having a discussion about the tone controls on a guitar.  It turns out that a bass tone control is just a high-pass filter made of a capacitor and a pot in series while a treble tone control is a low-pass filter with a pot and capacitor in parallel.  We understand the what, but don't understand the how.  How/why does the capacitor have this effect on a signal?  Maybe I'm missing the information in the article, but I don't see how the capacitor has this function.  Might be a good addition to the applications or some other section. -