Science
What is Capillary action?
Capillary action is the ability of a liquid to flow upward through narrow spaces against gravity, like water climbing up a thin tube or a paper towel. It happens because the liquid's molecules are attracted to the surface and to each other.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains capillary action.
Key things to understand
- 1Liquid rises through narrow spaces against gravity.
- 2It's driven by attraction to surfaces (adhesion) and itself (cohesion).
- 3Thinner tubes pull liquid higher.
- 4It's how plants draw water up and towels soak up spills.
Frequently asked questions
- What is capillary action?
- The movement of a liquid up through narrow spaces, against gravity, due to adhesion and cohesion.
- What's an example of capillary action?
- Water climbing up a paper towel, or a plant drawing water from roots up to its leaves.
- Why does capillary action work better in thin tubes?
- Narrower spaces increase the surface attraction relative to the liquid's weight, lifting it higher.