A metal detector is an electromagnetic tool that is used to pick up the sonar signal of metal that is hidden underground. There are many uses for metal detectors other than using them on the beach to find change. They are also used to find land mines this is called demining.

Metal detectors were first introduced in the 19th century, scientist wanted to come up with a way to make a machine find metals in the ground or that were buried. They came up with the metal detector and they have been used ever since.

The most common places you see metal detectors are in Airports, Courts and Federal buildings and in some schools. In the food industry a metal detector can locate any metal or foreign substances in food. Even on construction sites they can be used to find any steel bars that have been trapped in concrete, and pipes that may be found inside the walls.

The metal detector works like an oscillator that producing a current that passes through a coil that has a magnetic field. If there is any metal in the area of the magnetic field the detector will pick it up. You can also have fun with metal detectors on the beach or in a park.