A meniscus is a curve formed on the upper surface of a liquid inside a container. This curve is formed by the surface tension between the liquid and the container holding the liquid. If the molecules in the liquid are more attracted to the sides of the container than to each other, the liquid will stick to the sides of the container. When this happens, the meniscus curve bends down and is called concave. Most liquids form this kind of meniscus. Water is a common example of a liquid that forms a concave meniscus.
In some cases, the molecules of a liquid are more attracted to each other than the sides of the container, the liquid will pull away from the side of the container and form an upward curve, or convex meniscus. This type of meniscus is occasionally known as a ‘backward meniscus’, but the proper term is convex meniscus. A common liquid that forms a convex meniscus is liquid mercury.
How To Read A Meniscus
If the liquid forms a curve, how are you expected to make an accurate measurement of the amount of liquid in a container? To read a meniscus, you first need to see what type of meniscus your liquid forms. If the meniscus is a concave meniscus, read at the lowest level of the curve. If the meniscus is convex, take your measurement at the highest point of the curve.
The long answer: To read a meniscus, you first need to see what type of meniscus your liquid forms. If the meniscus is a concave meniscus, read at the lowest level of the curve. If the meniscus is convex, take your measurement at the highest point of the curve.
The short answer: Take your measurement from the center of the meniscus.
It’s that easy. Make sure to hold your container at eye level and read at the level of the center of the meniscus.
Bonus Meniscus Fun Fact
Meniscus is from the Greek word mēniskos meaning “crescent moon”.
Bonus Meniscus Fun Fact #2
The plural of meniscus is menisci.