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
Why do liquids have surface tension in a beaker?
Answer 1:

Surface tension in liquids is caused by attractive forces between the molecules of the liquid. These forces are called cohesive forces.
Water,for example, has polar molecules. This means that each molecule has a slightly negative charge at one end and a slightly positive charge at the other. The negatively charged end of one molecule is attracted to the positively charged end of another molecule, and the two ends "stick"together.
When you put liquid in a beaker, you probably notice that thesides of the liquid sit up kind of high on the sides of the beaker, forming what is called a meniscus. This happens because of an attraction between the glass and the liquid molecules. This attraction is called an adhesive force because it occurs between two unlike molecules. The adhesive force between the glass and the liquid is greater than the cohesive force between the liquid molecules; therefore, the liquid is pulled up the sides of the beaker toward the glass.
I hope this helps!


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 © 2015 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use