The , or metal detector, works by using electromagnetic induction to find metal objects underground. It sends an electromagnetic field into the ground via a transmit coil, and when this field encounters a metal object, it induces an electric current in the object. This current generates its own magnetic field, which is detected by a separate receive coil in the detector. The device then analyzes this signal to alert the user, often through an audio tone or a display on the screen, that a metal object is present.