A typical single-coil guitar pickup: copper wire wrapped around a bobbin which holds magnetic pole pieces adjacent to a magnetString effect on a single-coil (electric guitar). The coil is connected to a multimeter that indicates the voltage changes when the string moves. This signal is normally sent to an amplifier.
A single-coil pickup is a type of magnetic transducer, or pickup, for the electric guitar and the electric bass. It electromagnetically converts the vibration of the strings to an electric signal. Single-coil pickups are one of the two most popular designs, along with dual-coil or "humbucking" pickups.