Kids' Kitchen Walking Rainbow Experiment
The walking rainbow experiment is a fun and easy way to teach kids about the science of capillary action. Capillary action is the ability of a liquid to flow against gravity through a narrow tube or channel. In this experiment, we will use a paper towel to create a rainbow of colors that will walk up the paper towel.
Materials
* Paper towels
* Food coloring
* Water
* Glass jar or cup
Instructions
1. Cut a piece of paper towel into a strip about 1 inch wide and 12 inches long.
2. Fold the paper towel strip in half lengthwise.
3. Open up the paper towel strip and lay it flat on a table.
4. Add a few drops of food coloring to the bottom of the paper towel strip.
5. Place the paper towel strip in the glass jar or cup filled with water.
6. Watch the rainbow of colors walk up the paper towel strip.
Explanation
The water in the glass jar or cup is pulled up the paper towel strip by capillary action. Capillary action is caused by the adhesive forces between the water molecules and the paper towel fibers. The water molecules are attracted to the paper towel fibers and this attraction pulls the water up the paper towel strip. The different colors of food coloring travel at different speeds up the paper towel strip because they have different densities. The denser colors will travel more slowly than the less dense colors.
Tips
* For best results, use a thick paper towel.
* Add more food coloring to the bottom of the paper towel strip to make the colors more vibrant.
* Let the paper towel strip sit in the water for a few hours to allow the colors to fully walk up the paper towel strip.
Variations
* Try using different colors of food coloring.
* Make a rainbow of colors by using multiple paper towel strips.
* Add glitter to the water to make a sparkling rainbow.