Science Porn

[pocaracas]

Floating Water Bridge

When a high voltage is applied across two beakers filled with deionized water a phenomenon known as an electrohydrodynamic bridge can occur. The unsupported strand of water appears to defy gravity as the beakers are slowly separated. First demonstrated in 1893 by Sir William Armstrong, the floating water bridge has yet to be fully explained despite involving a number of important water science concepts.

The polar molecule water (H2O) has a permanent dipole moment and therefore acts as a dielectric fluid because it can be polarized in the presence of an applied electric field. The macroscopic behavior of the polarized fluid is governed by electrohydrodynamics, which describes several phenomena that occur as the magnitude of the electric field increases. These include an increase in meniscus height (electrowetting), bulk fluid circulation (Sumoto effect), and the ejection of charged droplets (electrospray). The electric field also exerts a force known as dielectrophoresis on the water molecules, which causes water to flow across the bridge and is likely involved in holding the stream together.

While this particular demonstration was performed using deionized water, any polar dielectric fluid could be used instead (e.g. glycerol or DMSO).

Also: