Levitating Objects In Paramagnetic Liquids

Two weekends ago was the Bay Area Maker Faire, and lacking a venue to talk to people who actually make things, we had a meetup at a pub. This brought out a ton of interesting people, and tons of interesting demos of what these people were building. By either proclivity or necessity, most of these demos were very blinkey. The demo [Grant McGregor] from Monterey Community College brought was not blinkey, but it was exceptionally cool. He’s levitating objects in paramagnetic liquids with permanent magnets.

Levitating objects in a paramagnetic solution around a magnetic field has been an intense area of research for the Whitesides Research Group for a few years now, with papers that demonstrate methods of measuring the density of objects in a paramagnetic solution and fixing diamagnetic objects inside a magnetic field. [Grant] is replicating this research with things that can be brought to a bar in a small metal box – vials of manganese chlorate with bits of plastic and very strong neodymium magnets. The bits of plastic in these vials usually float or sink, depending on exactly what plastic they’re made of. When the paramagnetic solution is exposed to a magnetic field, the density of the solution changes, making the bits of plastic sink or float.

It’s a bizarre effect, but [Grant] mentioned a nurd rage video that shows the effect very clearly. [Grant]’s further experiments will be to replicate the Whitesides Research Group’s experiment to fix a diamagnetic object inside a magnetic field. As for any practical uses for this effect, you might be able to differentiate between different types of plastic (think 3D printing filament) with just a vial of solution and a strong magnet.

[Grant] was heading out of the pub right when I ran into him, but he did stick around long enough to run into the alley behind the pub and record an interview/demo. You can check that out below.

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A DIY Geomagnetic Observatory

Magnetometer observatory

[Dr. Fortin] teaches physics at a French High School, and to get his students interested in the natural world around them, he built a geomagnetic observatory, able to tell his students if they have a chance at seeing an aurora, or if a large truck just drove by.

We’ve seen this sort of device before, and the basic construction is extremely similar – a laser shines on a mirror attached to magnets. When a change occurs in the local magnetic field, the mirror rotates slightly and the laser beam is deflected. Older versions have used photoresistors, but [the doctor] is shining his laser on a piece of paper and logging everything with a webcam and a bit of OpenCV.

The design is a huge improvement over earlier DIY attempts at measuring the local magnetic field, if only because the baseline between the webcam and mirror are so long. When set up in his house, the magnetometer can detect cars parked in front of his building, but the data he’s collecting (French, but it’s just a bunch of graphs) is comparable to the official Russian magnetic field data.

High Voltage Hacks: shrinking coins

The anthem for the Great Recession might be something along the lines of, “That we’re gonna do it anyway, even if doesn’t pay.” Some men just want to watch the world burn, so Hackerbot Labs posted a great walkthrough about shrinking coins and in the process making our pocket change worth just a little bit more.

Their build pushes 15,000 Joules (from a 10kV 300μF cap) through a coil of wire wrapped around a coin. This creates a magnetic field in the coil and the coin. These two fields repel each other, and there’s only one way that it can end: the coin shrinks and the coil of wire explodes. The team at Hackerbot Labs linked to a great theory of operations that does a great job explaining the physics has some awesome pictures.

During our research, we saw a few questions about the legality of altering currency. According to the U.S. Code, shrinking coins only illegal if it’s done fraudulently, like shrinking a penny down to the size of a dime to fool a pay phone or vending machine. Check out a video of the Hackerbot Labs setup putting as much energy as 100 heart defibrillators into a coin after the break.

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