| 单词 | capillarity | |||
| 释义 | capillaritycap·il·lar·i·tyC0084700 (kăp′ə-lăr′ĭ-tē)capillarity(ˌkæpɪˈlærɪtɪ)cap•il•lar•i•ty(ˌkæp əˈlær ɪ ti)n. capillarity
capillaritycapillarityorcapillary action,phenomenon in which the surface of a liquid is observed to be elevated or depressed where it comes into contact with a solid. For example, the surface of water in a clean drinking glass is seen to be slightly higher at the edges, where it contacts the glass, than in the middle. Capillarity can be explained by considering the effects of two opposing forces: adhesion, the attractive (or repulsive) force between the molecules of the liquid and those of the container, and cohesion, the attractive force between the molecules of the liquid (see adhesion and cohesionadhesion and cohesion,attractive forces between material bodies. A distinction is usually made between an adhesive force, which acts to hold two separate bodies together (or to stick one body to another) and a cohesive force, which acts to hold together the like or unlike ..... Click the link for more information. ). Adhesion causes water to wet a glass container and thus causes the water's surface to rise near the container's walls. If there were no forces acting in opposition, the water would creep higher and higher on the walls and eventually overflow the container. The forces of cohesion act to minimize the surface area of the liquid (see surface tensionsurface tension, tendency of liquids to reduce their exposed surface to the smallest possible area. A drop of water, for example, tends to assume the shape of a sphere. The phenomenon is attributed to cohesion, the attractive forces acting between the molecules of the liquid ..... Click the link for more information. ); when the cohesive force acting to reduce the surface area becomes equal to the adhesive force acting to increase it (e.g., by pulling water up the walls of a glass), equilibrium is reached and the liquid stops rising where it contacts the solid. In some liquid-solid systems, e.g., mercury and glass or water and polyethylene plastic, the liquid does not wet the solid, and its surface is depressed where it contacts the solid. Capillarity is one of the causes of the upward flow of water in the soil and in plants. capillarity[‚kap·ə′lar·əd·ē]capillary action, capillaritycapillaritycapillaritycapillarity[kap″ĭ-lar´ĭ-te]cap·il·lar·i·ty(kap'i-lar'i-tē),cap·il·lar·i·ty(kap'i-lar'i-tē)capillaritythe action by which the surface of a liquid (usually water) is elevated when in contact with a solid surface by attraction of molecules between the liquid and solid surfaces. When the liquid is in a narrow container (e.g. a capillary tube) the level of water will rise considerably, but capillarity can also occur in such structures as soils, causing a rise in the water table. Capillarity has been suggested as the explanation of water ascent in XYLEM vessels in plants, but is not considered to exert a significant effect. Compare COHESION/TENSION HYPOTHESIS, ROOT PRESSURE.cap·il·lar·i·ty(kap'i-lar'i-tē)capillarity
Synonyms for capillarity
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capillarity - a phenomenon associated with surface tension and resulting in the elevation or depression of liquids in capillaries