SCIENCE|natural and applied sciences|physical sciences|chemistry
- modh an fháinne Tagairt Faomhadh an téarma seo mar chuid de Thionscadal Lex
- ga
- Ringmethode
- de
- Sainmhíniú Verfahren zur Messung der Oberflächenspannung, bei dem die Flüssigkeit angehoben wird, bis ein Kontakt des Rings mit der Oberfläche erfolgt, und anschließend die Probe wieder abgesenkt wird, so dass unter dem Ring eine Flüssigkeitslamelle entsteht Tagairt "auf der Grundlage von KRÜSS GmbH, ""Oberflächenspannung : Ringmethode"", Krüss GmbH, Hamburg, ca. 2010, http://www.kruss.de/theorie/messungen/oberflaechenspannung/ringmethode.html (17.08.2010)"
- ring method
- en
- Sainmhíniú the liquid is raised until contact with the surface is registered. The sample is then lowered again so that the liquid film produced beneath the ring is stretched. As the film is stretched a maximum force is experienced; this is recorded in the measurement. At the maximum the force vector is exactly parallel to the direction of motion; at this moment the contact angle θ is 0°. In practice the distance is first increased until the area of maximum force has been passed through. The sample vessel containing the liquid is then moved back so that the maximum point is passed through a second time. The maximum force is only determined exactly on this return movement and used to calculate the tension.The calculation is made according to the following equation: σ = Fmax-FV / L∙cosθwhereσ = surface or interfacial tensionFmax = maximum forceFV = weight of volume of liquid liftedL = wetted lengthθ = contact angleThe contact angle θ decreases as the extension increases and has the value 0° at the point of maximum force, this means that the term cosθ has the value 1 Tagairt "KRÜSS Advancing Surface Science: Ring Method http://www.kruss.de/en/theory/measurements/surface-tension/plate-method.html [3.12.2009]"
- Nóta The film breakage is avoided during the measurement in most cases. Nevertheless, the point of film breakage can also be measured with the “Ring-Tear-off”-Method.Correction calculations are necessary with the ring method.