Hand Held Metal Detector

High quality hand held metal detectors will find concealed knives and weapons, foil wrapped drugs and other concealed metallic objects. … It is the movement of the electromagnetic field that induces further electromagnetic fields around concealed metal objects.

A metal detector is an electronic instrument that detects the presence of metal nearby. Metal detectors are useful for finding metal inclusions hidden within objects, or metal objects buried underground. 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.