Metal detectors can be used to detect various metal objects. Metal detector is an electronic instrument for detecting the presence of nearby metals. The simplest form of metal detector consists of an oscillator that generates alternating current through a coil that generates alternating magnetic fields. If a conductive metal is close to the coil, it will generate eddy currents in the metal, which will generate its own magnetic field. If another coil is used to measure the magnetic field (used as a magnetometer), changes in the magnetic field caused by metal objects can be detected. Metal detectors can be used to locate metal inclusions hidden in objects or metal objects buried underground. They are usually composed of hand-held devices with sensor probes that can sweep across the ground or other objects. If the sensor is close to a piece of metal, the pointer on the pointer moves, or the detection instrument will show changes, the metal detector will be used for security checks at access points in prisons, courts and airports to detect hidden metal weapons on the human body.
Metal detectors are widely used in mineral exploration and other industrial applications. Uses include detection of mines, detection tools and other weapons, geophysical exploration, Archaeology and treasure hunting. Metal detectors are also used to detect foreign bodies in food, and in the construction industry to detect steel bars in concrete and pipelines and wires buried in walls and floors.