Toward an Understanding of Magnetic Displacement of Floating Diamagnetic Bodies, I: Experimental Findings

Diamagnetic
objects (polymer and metallic plates and spheres, ceramic
beads, and liquid marbles), floating on water, and a variety of organic
liquids may be driven by a steady magnetic field of 0.1 T, registered
at the water–vapor surface. Diamagnetic bodies are attracted
to the magnet, when the apparent contact angle at the solid/liquid
interface is obtuse and repelled from the magnet, when the angle is
acute. Cold plasma-treated polyolefin rafts and spheres, demonstrating
underwater floating, are repelled by a permanent magnet. Addition
of a surfactant to the water, as well as cold plasma treatment of
the polyolefin bodies, can turn the attraction into the repulsion.
We conjecture that the observed effects are caused by the interplay
of two main phenomena. The first is the gravity, which induces sliding
of the particle on the deformed liquid/vapor interface (the Moses
effect). The second cause is the hysteresis of the contact angle at
the bodies’ boundaries.