Beer Cans and Metal Detectors

metal detectors

Back in 2008 there was a really, really, bad movie called Fool’s GoldIn one scene, a perpetually shirtless Matthew McConaughey uses a metal detector to discover an aluminum beer can which reveals some dumb clue relevant to the even dumber plot of the movie.

Why, you may ask, are we bringing up this garbage committed to film a full ten years later? Because a lot of customers asked us then, and randomly, another asked us recently, if metal detectors actually detect aluminum. Given that beach season is upon us, and there are a lot of people who like to prowl said beaches, metal detectors in hand, we figured we’d address that.

metal detectors

How do metal detectors even work?

In short, they generate a magnetic field with a coil which then passes over the metals. These generate magnetic fields of their own which the detector, well, detects.

The long answer involves utilizing oscillator fields and eddy currents as illustrated by great Scottish physicist James Clerk Maxwell’s equation of electromagnetism and… never mind, we’ll stick to the short answer.

Seriously though, to give some credit where it’s due, Maxwell was a genius. Even if the science is over our heads, we should all be thankful for the man. Einstein said there is only one person more influential in science and modern life than Maxwell. That person is Sir Isaac Newton. Plus, Maxwell had a rockin’ beard.

metal detectors

James Clerk Maxwell (1831 – 1879)

Back to the aluminum can though. A lot of folks mistakenly believe that such electrical currents only work with ferrous metals like iron and steel. However, this isn’t actually the case! Technically all metals are magnetic. Many are only slightly magnetic or are magnetic at really high or low temperatures. This means that these metals react to the electrical and magnetic fields generated by metal detectors. As such, yes, McConaughey actually would have been able to detect a beer can with his metal detector! Probably the only believable or realistic part of that whole movie.

DIY Metal Detectors?

Want to have your own treasure hunting adventures? Don’t fancy shelling out lots of money for a professional detector? Just want a cool little toy to show off to your friends? Lucky for you, there are many different options!

The easiest way just requires a smartphone. There are coders who have developed apps that alloy your smartphone to use internal sensors to act as a metal detector. While cool, that’s kind of less exciting.

The next easiest way requires, no joke, an AM radio and a calculator. By strapping those things together you have yourself a crude but effective handheld metal detector! You can also strap that contraption to a broom handle or any other sort of non-metallic pole and make a metal detector that doesn’t requite you to scuttle around like a crab to use it.

metal detectors

If you’e got a little more time, gear, and technical know-how, you can make something that looks more like a classic metal detector.

To the people who were here more for beer cans than metal detectors but stayed and read all the way through, first, thank you. Second, I’ve got something for you too! If you’re feeling outdoorsy, you can use those cans for more than just alcohol-fueled fun, you can use them for a different sort of alcohol-fueled fun and turn them into little miniature stoves that easily fit in a pocket. It’s pretty cool and easy too.

Have a great summer, have fun, and if you make any of these things, please let us know on Facebook or Twitter!