Capillary action facts for kids
Capillary action is a cool way liquids move on their own! It's like a secret force that pulls liquids up or into small spaces. You can see it happen in two main ways:
- When a liquid moves up inside a very thin tube.
- When a liquid soaks into something with many tiny holes, like a sponge.
This amazing action happens because of something called surface tension. Liquids have a kind of "skin" on their surface, which is the surface tension. This "skin" helps pull the liquid along.
Contents
How Capillary Action Works
Capillary action is all about how liquids stick to surfaces and to themselves.
Sticking to Surfaces: Adhesion
Imagine a drinking straw in a glass of water. You might notice the water level inside the straw is a little higher than the water outside. This happens because water molecules like to stick to the straw's surface. This "sticking" is called adhesion.
Sticking to Itself: Cohesion
At the same time, water molecules also like to stick to each other. This is called cohesion. The force of adhesion (water sticking to the straw) is a bit stronger than gravity pulling the water down. So, the water molecules pull each other up the straw, thanks to cohesion.
Capillary Action in Everyday Life
You can see capillary action all around you, even if you don't always notice it!
Sponges and Paper Towels
Think about putting a sponge into a puddle of water. The water quickly gets sucked into the sponge. This is capillary action at work! A sponge has many tiny holes, like lots of tiny straws packed together. When the sponge touches water, the water goes into these holes. The tiny spaces inside the sponge pull the water in. Paper towels work the same way, soaking up spills quickly.
Plants and Trees
Capillary action is super important for plants. It helps them get water from their roots all the way up to their leaves, even in tall trees! Tiny tubes inside the plant's stem pull water upwards against gravity.
Inside Your Body
Capillary action even happens inside the human body! For example, it helps remove tears from your eyes. Tiny tear ducts use capillary action to drain away extra tears.
Images for kids
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Effect of placing a porous brick in a shallow tray of water
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Rising-damp.jpg
Moderate rising damp on an internal wall
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Water height in a capillary plotted against capillary diameter
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Capillary flow in a brick, with a sorptivity of 5.0 mm·min−1/2 and a porosity of 0.25.
See also
In Spanish: Capilaridad para niños
