| Adhesion |
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Adhesion, the clinging of one substance to another, also plays a role. Adhesion of water to the walls of the cells helps counter the downward pull of gravity. Water molecules interact with other polar materials, such as glass, through adhesive forces, forces of attraction between molecules of two different substances. Glass being a polar substance, there are adhesive forces between glass and water. These adhesive forces are relatively strong, and the water molecules adjacent to the inner surface of a glass container seem to climb up the inner surface of the glass above the water surface. Hence the water is curved up the sides of the glass. This curving of the water surface (or the surface of any other liquid) at the interface between it and its container is called a meniscus.
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Adhesive forces between water and glass cause water molecules to creep up the sides of the glass, forming a meniscus. |
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