Electronic instrument which detects the presence of metal nearby
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U.S. Army soldiers use a military standard metal detector
A metal detector is an instrument that detects the nearby presence of metal. Metal detectors are useful for finding metal objects on the surface, underground, and under water. A metal detector consists of a control box, an adjustable shaft, and a variable-shaped pickup coil. When the coil nears metal, the control box signals its presence with a tone, light, or needle movement. Signal intensity typically increases with proximity. Another common type are stationary "walk through" metal detectors used at access points in prisons, courthouses, airports and psychiatric hospitals 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 (inductive sensor) in the metal, and this produces a magnetic field of its own. If another coil is used to measure the magnetic field (acting as a magnetometer), the change in the magnetic field due to the metallic object can be detected.
The first industrial metal detectors came out in the 1960s. They were used for finding minerals among other things. Metal detectors help find land mines. They also detect weapons like knives and guns, which is important for airport security. People even use them to search for buried objects, like in archaeology and treasure hunting. 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.
A metaldetector is an instrument that detects the nearby presence of metal. Metaldetectors are useful for finding metal objects on the surface, underground...
which (ground penetrating radar) has been employed in tandem with metaldetectors. Acoustic methods can sense the cavity created by mine casings. Sensors...
and reception of communication signals, or for detection of metal objects in metaldetectors or vehicle presence indicators. A common modern use for induction...
between a crystal and a metal was discovered in 1874 by Karl Ferdinand Braun. Crystals were first used as radio wave detectors in 1894 by Jagadish Chandra...
According to some accounts, the metaldetector worked flawlessly in tests but did not find Guiteau's bullet, partly because the metal bed frame on which the President...
The Mine detector (Polish) Mark I (Polish: wykrywacz min) was a metaldetector for landmines developed during World War II. Initial work on the design...
noun or a noun phrase. Take the English examples heavy metaldetector and heavy-metaldetector. The former example contains only the bare adjective heavy...
nugget of fine-quality[vague] that was found by Kevin Hillier using a metaldetector near Kingower, Victoria, Australia on 26 September 1980. Weighing 875...
metal allergies. Women wearing an underwire bra have in a few rare instances been subjected to extra scrutiny when their bra set off metaldetectors at...
archaeologists are most successful with metaldetectors when using them in large groups. Novice users of metaldetectors can easily miss or record misleading...
as metaldetectors: they can detect only magnetic (ferrous) metals, but can detect such metals at a much greater distance than conventional metal detectors...
became the fifth Republican representative to be fined for evading metaldetectors put in place outside the chamber after the January 2021 storming of...
most commonly by members of the public with the use of a commercial metaldetector. Nighthawking breaks the law on a number of points: Trespass: Nighthawking...
large bulge in his pants. According to Falcon, after passing through a metaldetector and a body scanner, he was selected for additional screening, after...
This is a list of historically significant items found by metal detecting method, only excluding magnet fishing finds, since magnet fishing is usually...
"Children Of Bodom: MetalDetector". Metal Hammer. Retrieved 5 April 2022. Lawson, Dom. "The 10 essential melodeath albums". Metal Hammer. Retrieved 25...
gas sensors, photoionization detectors, infrared point sensors, ultrasonic sensors, electrochemical gas sensors, and metal–oxide–semiconductor (MOS) sensors...
Stringer district near Randsburg by prospector Ty Paulsen in 1977 using a metaldetector. The nugget, which weighs 156 troy ounces (4.9 kg), is part of the Margie...
began the installation of an "electro-magnetic gun or metal detecting system" at Alcatraz; detectors were added on the wharf, at the front entrance into...
the team returns to Oak Island and begins searching the swamp with a metaldetector again while it is covered with ice and snow. A large target is identified...
alarm system. Traditional smoke detectors are ionization smoke detectors which create an electric current between two metal plates, which sound an alarm...
formal archaeological use of metaldetectors include musketball distribution analysis on English Civil War battlefields, metal distribution analysis prior...
or the single rider queue. As of 2015, riders must pass through a metaldetector in order to board, and may not board with any loose items on their person...
an American privately held company that specialises in walk-through metaldetectors and X-ray machines for screening airport luggage and cargo. The company...
of composite material so as to evade metaldetectors, and he can carry two small bullets past a metaldetector concealed in a key-ring ornament. He is...
Hill metaldetectors, and entered the Capitol. She did the same on January 6, refusing to stop for a wand check after she set off the metaldetector. Boebert...
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