Metal Detector

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



The operation of metal detectors is based upon the principles of **electromagnetic induction**. Metal detectors contain **inductor coils** that interact with metallic pieces on the ground. Inside the **metal detector's loop** the **transmit coil** is placed. **Electronic current** is driven through the coil to create an **electromagnetic field**.



When the current flows in a given direction, a **magnetic field** is produced, which polarity points into the ground. When the current flow is reversed, the field's polarity points out of the ground. Any metallic object will then have a flow of current induced inside of it. *This current inside a metal object in turn produces its own magnetic field, with a polarity that tends to be pointed opposite to the transmit field*. This magnetic field creates **electric impulses** in the **second (receiving) coil** of the detector.