A metal detector is an electronic instrument which detects the presence of metal nearby.
An electronic musical instrument is a musical instrument that produces sound using electronic circuitry andor listener.
A metal is a material that is typically hard, opaque, shiny, and has good electrical and thermal conductivity.
Metal Detecting the Lake Sandbar! by nuggetnoggin
Metal detectors are useful for finding metal inclusions hidden within objects, or metal objects buried underground.
Aquachigger: What Metal Detectors Does He Use? My Top Choices. by Aquachigger
They often consist of a handheld unit with a sensor probe which can be swept over the ground or other objects.
If the sensor comes near a piece of metal this is indicated by a changing tone in earphones, or a needle moving on an indicator.
Usually the device gives some indication of distance; the closer the metal is, the higher the tone in the earphone or the higher the needle goes.
Another common type are stationary "walk through" metal detectors used for security screening at access points in prisons, courthouses, and airports to detect concealed metal weapons on a person's body.
The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field.
If a piece of electrically conductive metal is close to the coil, eddy currents will be induced in the metal, and this produces a magnetic field of its own.
Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction.
If another coil is used to measure the magnetic field, the change in the magnetic field due to the metallic object can be detected.
The first industrial metal detectors were developed in the 1960s and were used extensively for mineral prospecting and other industrial applications.
Prospecting is the first stage of the geological analysis of a territory.
Uses include detecting land mines, the detection of weapons such as knives and guns, geophysical prospecting, archaeology and treasure hunting.
A land mine is an explosive device concealed under or on the ground and designed to destroy or disable enemy targets, ranging from combatants to vehicles and tanks, as they pass over or near it.
Treasure is a concentration of riches, often those that originate from ancient history, considered lost and/or forgotten until being rediscovered.
Archaeology, or archeology, is the study of human activity through the recovery and analysis of material culture.
Metal detectors are also used to detect foreign bodies in food, and in the construction industry to detect steel reinforcing bars in concrete and pipes and wires buried in walls and floors.
Construction is the process of constructing a building or infrastructure.