Meniscus
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2008-07-16T15:39:22Z
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:''For other uses, see: [[meniscus (anatomy)]] and [[Lens (optics)#Lens construction|lens (optics)]].''
[[Image:Reading the meniscus.png|thumb|300px|'''A:''' The ''bottom'' of a concave meniscus.<br>'''B:''' The ''top'' of a convex meniscus.]]
'''Meniscus''', plural: ''menisci'', from the [[Greek language|Greek]] for "crescent", is a curve in the surface of a liquid and is produced in response to the surface of the container or another object. It can be either [[convex set|concave or convex]]. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the container.<ref> Moore, John W.; Stanitski, Conrad L.; Jurs, Peter C. Chemistry: The Molecular Science. Belmont, CA: Brooks/Cole, 2005. 290.</ref> This may be seen between [[Mercury (element)|mercury]] and [[glass]] in barometers.<ref> Moore, John W.; Stanitski, Conrad L.; Jurs, Peter C. Chemistry: The Molecular Science. Belmont, CA: Brooks/Cole, 2005. 290.</ref> Conversely, a concave meniscus occurs when the molecules of the liquid attract those of the container. This can be seen between [[water]] and [[glass]]. [[Capillary action]] acts on concave menisci to pull the liquid up, and on convex menisci to pull the liquid down. This phenomenon is important in [[transpirational pull]] in [[plant]]s.Honey, water, milk etc. have a lower meniscus . When a tube of a narrow bore, often called a capillary tube, is dipped into a liquid and if the liquid “wets” the tube (with zero contact angle), the liquid surface inside the tube forms a concave meniscus, which is a virtually spherical surface having the same radius, r, as the inside of the tube. The tube experiences a downward force of magnitude 2πrdσ .Mercury etc. have a upper convex meniscus.
When reading a scale on the side of a container filled with liquid, the meniscus must be taken into account in order to obtain a precise measurement. Manufacturers take the meniscus into account and calibrate their measurement marks relative to the resulting meniscus. The measurement is taken with the meniscus at eye level to eliminate [[parallax error]], and at the central point of the curve of the meniscus, i.e. the top of the meniscus, in the unusual case of a liquid like mercury, or more usually, the bottom of the meniscus in water and most other liquids.
==References==
{{reflist}}
==See also==
* [[Capillary action]]
* [[Contact angle]]
* [[Surface tension]]
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