UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
What shape is the surface of water in a container? This is a question about the meniscus. I think it curves up at the sides. Is that right?
Question Date: 2003-01-26
Answer 1:

Thanks for the question. You are correct. It is called the meniscus, but let me give you some more information on the subject.

A meniscus is the curved surface at the top of a column of liquid. In a science class, this liquid is usually water or some sort of aqueous solution, and the column is usually a graduated cylinder or a pipet. As you may have noticed, when water is in such a thin glass tube, it does not have a flat surface at the top. Instead, the top is curved inward, making it a little difficult to decide exactly where to read the volume. The volume should be read from the bottom of the meniscus.

Why doesn't water lie flat? Well, it has to do with the nature of the water molecules and glass molecules themselves. Water is made up of polar molecules, which have positively and negatively charged ends. Since opposites attract, the positive sides attract the negative sides, and all of the molecules stick to one another. This is why water droplets can form. Glass molecules also happen to be polar. Again, since polar molecules like to stick together, the water in a glass tube will actually tend to stick to the sides of the tube! You can see this at the top of the graduated cylinder, where the water will slightly creep up the sides and form a curve, which is the meniscus.



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use