Guitars Not Metal Detectors

So our physics class had a test on magnets, electromagnets, and how they work to make a lot of things function in this world. One of the questions on the test was how a metal detector in an airport works. At the time of the test, I had no idea how it worked but later as I stared at my beautiful epiphone wildcat electric guitar I realized basically the same ideas are involved. Too bad I could not figure that out then; I had a total mind blank on that test. So how the guitar works is based off the idea of electromagnetic induction. A totally simple process that consist of permanent magnets, strings, and coil wrap around those magnets. A solid body or even a semi-hallow bodied electric guitar consists of these materials so it can be heard out of an amplifier so you can rock out with jimi, stevie ray, morello, synyster gates, or any other ill guitar player that has every existed. The pick ups on the guitar are the permanent magnets and under the surface of the guitar the magnets are wrapped in tightly wound coil. When a string is plucked or picked the magnetic field from the permanent magnet in the pick up beneath that string is felt by the vibrating string and induces a current into the string because the moving string feels a changing magnetic field as it is vibrating. In turn the string, now being a magnet, has a magnetic field of its own and the wrapped coil beneath the surface of the guitar gains a current by induction from the vibrating string of the same frequency and flows out through the guitar wire into the amp and is heard by all out of the speakers of the amp (wow that was a long sentence). Guitars are way cooler than metal detectors!