Capillary Action
![Many testing tubes on a stand](/media/libraries/college-of-science-and-engineering/physics/images/demo-images/CapillaryAction.jpg)
PIRA: 2A20.10
The capillary action demonstration consists of 7 glass tubes of varying inner diameter. By placing each tube in a little bit of water or alcohol, the demonstrator can show that fluids can climb a tube without any suction. The effectiveness of a capillary tube is related to the tube's inner diameter and the nature of the fluid involved. Adding a little bit of dish soap to the water results in a dramatic change in it's capillary behavior. Adding a few drops of food coloring makes this demo much more visually effective.