What is a Metal Detector?
Metal detectors use electromagnetic induction to detect metal. Most of us link of people combing the beach or the park when we think of metal detectors, but this is not the extent of their utility. The best metal detectors are also utilized in de-mining, the detection of weapons such as knives and guns, especially at airports, geophysical prospecting, and archaeology.
In its simplest form, 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 an alternating magnetic field of its own. If another coil is used to measure the magnetic field, the change in the field created by the metallic object can be detected.