The tutor gives a nontechnical explanation of how a metal detector functions.

Watching Curse of Oak Island on the History channel, you see them use metal detectors.

How does a metal detector work? A basic explanation is this:

1. The search coil has electricity passing through it so that it emits a magnetic field.
2. A characteristic of metals (as opposed to nonmetals) is that their electrons are moved by a magnetic field.
3. As the metal object’s electrons move, they change the electromagnetic environment. It’s a kind of “rebound” effect.
4. The detector has a detection coil that senses the electromagnetic rebound broadcast from the movement of the metal’s electrons.

Source:

electronics.howstuffworks.com