Water thread experiment

The water thread experiment is a phenomenon that occurs when two containers of deionized water, placed on an insulator, are connected by a thread, then a high-voltage positive electric charge is applied to one container, and a negative charge to the other. At a critical voltage, an unsupported water liquid bridge is formed between the containers, which will remain even when they are separated. The phenomenon was first reported in 1893 in a public lecture by the British engineer William Armstrong.^[1]

The bridge as observed in a typical configuration has a diameter of 1–3 mm so the bridge remains intact when pulled as far as 25 millimetres (0.98 in), and remains stable up to 45 minutes. The surface temperature also rises from an initial surface temperature of 20 °C (68 °F) up to 60 °C (140 °F) before breakdown.

Experiment

In a typical experiment, two 100 mL beakers are filled with deionized water to roughly 3 mm below the edge of the beaker, and the water exposed to 15 kV direct current, with one beaker turning negative, and the other positive. After building up electric charge, the water then spontaneously rises along the thread over the glass walls and forms a "water bridge" between them. When one beaker is slowly pushed away from the other, the structure remains. When the voltage rises to 25 kV, the structure can be pulled apart as far as 25 millimetres (0.98 in). If the thread is very short, then the force of the water may be strong enough to push the thread from the positive glass into the negative glass.

The water generally travels from anode to cathode, but the direction may vary due to the different surface charge that builds up at the water bridge surface, which will generate electrical shear stresses of different signs. The bridge breaks into droplets due to capillary action when the beakers are pulled apart at a critical distance, or the voltage is reduced to a critical value.

The bridge needs clean, deionized water to be formed, and its stability is dramatically reduced as ions are introduced into the liquid (by either adding salt or from electrochemical reactions at the electrode surface).

Causes

Although the phenomenon still needs to be studied further, the scientific community agrees that surface polarization at the water surface when a high tangent electrical field is applied is responsible for the extraordinary stability of the system, which has been confirmed via experiments, theory and simulations.^[2][3][4] The same mechanism has been known for decades and has been applied for stabilization of liquid films and oil liquid bridges in the past.^[5][6] Some have speculated that this bridge is made of up an H₃O₂ lattice or exclusion zone water.^[7] However, there is no single experimental proof or measurement of such claims.

References

• Marin, Alvaro; Lohse, Detlef (15 December 2010). "Building water bridges in air: Electrohydrodynamics of the floating water bridge". Physics of Fluids. 22 (12): 122104–122104–9. arXiv:1010.4019. Bibcode:2010PhFl...22l2104M. doi:10.1063/1.3518463. S2CID 119215447. Retrieved 2010-12-23.
• Aerov, Artem (2011). "Why the water bridge does not collapse". Physical Review E. 84.3 (36314): 036314. arXiv:1012.1592. Bibcode:2011PhRvE..84c6314A. doi:10.1103/PhysRevE.84.036314. PMID 22060499. S2CID 29889217.
• Morawetz, Klaus (2012). "Theory of water and charged liquid bridges". Physical Review E. 86.2 (26302): 026302–1. arXiv:1107.0459. Bibcode:2012PhRvE..86b6302M. doi:10.1103/PhysRevE.86.026302. PMID 23005849. S2CID 42770937.
• González, H.; Mccluskey, F. M. J.; Castellanos, A.; Barrero, A. (26 April 2006). "Stabilization of dielectric liquid bridges by electric fields in the absence of gravity". Journal of Fluid Mechanics. 206 (1): 545. Bibcode:1989JFM...206..545G. doi:10.1017/S0022112089002405.
• Sankaran, Subramanian; Saville, D. A. (April 1993). "Experiments on the stability of a liquid bridge in an axial electric field". Physics of Fluids A: Fluid Dynamics. 5 (4): 1081–1083. Bibcode:1993PhFlA...5.1081S. doi:10.1063/1.858625.
• Pollack, Gerald. "Exclusion Zone Water". University of Washington.
• Beaty, William (1996). "Wasserfadden Experiment (Water threads)". www.amasci.com. Retrieved 2007-01-20.
• Hammond, Richard (2006). "Can you feel the Force?". Dorling Kindersley.
• Fuchs, Elmar C.; Woisetschläger, Jakob; Gatterer, Karl; Maier, Eugen; Pecnik, René; Holler, Gert; Eisenkölbl, Helmut (21 September 2007). "The floating water bridge". J. Phys. D: Appl. Phys. 40 (19): 6112–6114. Bibcode:2007JPhD...40.6112F. doi:10.1088/0022-3727/40/19/052. Retrieved 2007-09-29.
• Zyga, Lisa (2007-09-28). "Water forms floating 'bridge' when exposed to high voltage". Science News. Retrieved 2007-09-29.
• Ponterio, R.C.; M. Pochylski; F. Aliotta; C. Vasi; M.E. Fontanella; F. Saja (2010). "Raman scattering measurements on floating water bridge" (PDF). Journal of Physics D: Applied Physics. 43 (17): 175405. Bibcode:2010JPhD...43q5405P. doi:10.1088/0022-3727/43/17/175405.
• Skinner, L.B.; C. Benmore; B. Shyam; J.K.R. Weber; J.B. Parise (2012). "Structure of the floating water bridge and water in an electric field". Proc. Natl. Acad. Sci. 109 (41): 16463–16468. Bibcode:2012PNAS..10916463S. doi:10.1073/pnas.1210732109. PMC 3478597. PMID 23010930.

This page was last edited on 20 November 2023, at 13:25