Do you like to spend time at the beach? Of course you do! Who doesn't? What do you like to do at the beach? Swim? Sunbathe? Build sand castles?
Did you know that some people like to search for buried treasure on the beach? Have you ever seen someone walking along the beach carrying a long stick pointed toward the sand? They may have also been wearing headphones connected to the long stick. What were they carrying? A detector, of course!
detectors can be used to detect objects hiding under the sand. The ultimate score would be a large chest filled with long-lost treasure. More likely, though, you'll find coins dropped by beachgoers.
Large detectors shaped like doorways or handheld wands are also used in airports and other buildings to help security personnel scan for weapons and other items that could pose a risk to safety. So just how exactly do these things tell what's and what isn't?
Most detectors produce an audible signal when is detected. That's why those people on the beach wear headphones connected to their handheld detector units.
Very low frequency technology, also known as VLF or induction balance, is arguably the most popular detection technology in use today. VLF technology uses two coils that create an electromagnetic field. When this field encounters an object that conducts electricity, such as , the object's own magnetic field is detected. This causes the detector to emit an alert that a object has been detected.
Since most detectors must detect a object's magnetic field, objects need to be fairly close to the surface (within about a foot or so) to be detected by inexpensive detectors. More advanced — and expensive — detectors can detect things buried much deeper. Advanced detectors can also provide information about what types of metals are below the surface.