Today’s Wonder of the Day was inspired by Heather. Heather Wonders, “Why are metal detectors made out of metal?” Thanks for WONDERing with us, Heather!

Do you like going to the beach? Of course you do! Who doesn’t? What do you do at the beach? Swim? Sunbathe? Build sandcastles?

Did you know that some people like to search for buried treasure on the beach? It’s true! They even use a special tool to find hidden objects. Have you ever seen a person walking along the beach with a long metal stick pointed toward the sand? They may have also been wearing headphones connected to the long metal stick. What were they carrying? A metal detector, of course!

Metal detectors can find hidden metal objects. The ultimate score would be a large metal chest filled with long-lost treasure. More likely, though, they’ll find coins dropped by other people on the beach.

Most metal detectors make a sound when they find metal. That’s why those people on the beach wear headphones connected to their handheld metal detector units. When they hear the metal detector beeping, they know a treasure could be just under their feet!

You may have also seen different kinds of metal detectors in airports and other buildings. They’re often large and shaped like doorways. Sometimes, security officers even carry handheld wands that detect metal. These scan for weapons and other items that could be a risk to safety. So, just how exactly do these things tell what’s metal and what isn’t?

Most metal detectors use very low-frequency technology, also known as VLF. This technology uses two coils that make an electromagnetic field. When the field finds an object that conducts electricity, the object’s own magnetic field is detected. That’s when the detector alerts that it has found a metal object.

Objects need to be fairly close to the surface (within about a foot or so) to be detected by inexpensive metal detectors. More advanced metal detectors find things buried much deeper. Advanced metal detectors can also provide information about what types of metals are below the surface.

Do you dream of finding buried treasure one day? A metal detector could definitely help. People have made some pretty incredible finds over the years using a metal detector. How would you like to discover ancient Viking treasure? How about long-lost royal jewelry? Someone once even found a piece of meteor using a metal detector! On your next visit to the beach, consider taking a metal detector along. You never know what might be waiting for you just below the sand!

Standards: CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1

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