| Capillary Action |
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A common Apparatus used to demonstrate capillary action is the ''capillary tube''. When the lower end of a Vertical Glass tube is placed in a liquid such as Water , a concave meniscus forms. Surface Tension pulls the liquid column up until there is a sufficient Weight of liquid for Gravitational Force s to overcome the intermolecular forces. The weight of the liquid column is Proportional to the Square of the tube's Diameter , but the Contact Area between the liquid and the tube is proportional only to the diameter of the tube, so a narrow tube will draw a liquid column higher than a wide tube. For example, a Glass capillary tube 0.5 Mm in diameter will lift a theoretical 2.8 cm column of water. Actual observations show shorter total distances. With some pairs of Materials , such as Mercury and glass, the interatomic forces within the liquid exceed those between the solid and the liquid, so a Convex meniscus forms and capillary action works in reverse. A Plant makes use of capillary action to draw liquid Water into its system, although larger plants require Transpiration to Move a Sufficient Quantity of Water to where it is required. In Hydrology , capillary action describes the attraction of Water molecules to soil particles. Capillary action is responsible for moving water from wet areas of the soil to dry areas. FORMULA With notes on the dimension in SI units, the height ''h'' of a liquid column ( M ) is given by: : ...where: T θ ρ g r For a water-filled glass tube in Air at Sea Level , T θ ρ g ...and so the height of the water column is given by: :. TRIVIA Albert Einstein 's first paper submitted to Annalen Der Physik was on capillarity. It was titled ''Folgerungen aus den Capillaritätserscheinungen'', which translated is ''Consequences of the observations of capillarity phenomena'', found in volume 4, page 513. Submitted in late 1900, it was published in 1901. In 1905 Einstein published five seminal papers in the same journal. SEE ALSO |
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