Ferrofluid Forcefield Experiment

Since this experiment didn't go quite the way we expected, we didn't make a video of it (sorry guys). However, on a positive note, we succeeded in narrowing down the potential hoverboard possibilities by one more! The purpose here was to create a spinning vortex of ferrofluid (a magnetic liquid), suspend it from a neodymium magnet (the strongest rare-earth magnet there is), and hope it proves strong enough to contain air pressure. What we got was a bowlful of splattered ferrofluid and a lesson in basic Newtonian physics.

Procedure

The experiment involved attaching a 1.5" x 3/8" neodymium ring magnet to an electric motor with a speed control circuit that allowed us to slowly increase the speed from 120 to over 16,000 rpm. A clear plastic dish was attached directly to the magnet to hold the ferrofluid, the black substance seen in the photo on the right. Notice how it conforms to the shape of the magnetic field.

Results

What we were expecting to produce was a cone-shaped vortex resulting from the combined centrifugal and gravitational forces acting on the ferrofluid. Instead, we found the majority of the force was centrifugal causing the fluid to flatten rather than lengthen. As the motor speed was increased, the centrifugal force on the fluid ultimately exceeded the magnetic force on it, creating the splattered mess you see on the right.

Conclusions

Ferrofluid does not make a good forcefield. Also, since it is oil-based, it is very messy and will leave an oily residue. A water-based ferrofluid can be purchased through Ferrotec, however it doesn't come cheap. We bought a 50ml bottle of oil-based ferrofluid through Forcefield for $25, but $5 per ml, the price Ferrotec charges, leaves us scratching our heads.