Capacitive switches are used in many applications where it is important to know if an object has been touched or not. These switches can be used as part of a control system, such as a door lock, or they may be used as a sensor, such as an elevator button. The capacitive switch consists of two plates separated by a dielectric medium. When the top plate touches the bottom plate, the capacitor is closed and current flows through the circuit. If the top plate is removed from the bottom plate, the switch becomes open and no current will flow.