Running Rainbow

Watch Water Walk – Create a Rainbow with Capillary Action!

Have you ever seen water “walk” from one cup to another? With a simple setup of cups and paper towels, you can create a beautiful rainbow effect while exploring the fascinating science of capillary action. This colorful experiment is both fun and educational!

Materials You’ll Need

• 5 clear cups or glasses (3 for the three colors and 2 for plain water)

• Water – enough to fill three cups about 3/4 full

• Food coloring – red, yellow, and blue (1 drop per cup)

• Paper towels – cut into strips (enough to connect the cups)

• Spoon (for mixing)

Step-by-Step Tutorial

1. Prepare the Cups: Place 5 cups in a row. Fill the three middle cups (1, 3, and 5) with water, leaving cups 2 and 4 empty.

2. Add Food Coloring: Add a drop of red food coloring to cup 1, a drop of yellow to cup 3, and a drop of blue to cup 5. Stir gently with a spoon to mix the colors.

3. Connect the Cups: Take strips of paper towel and place one end in each of the colored cups (1, 3, and 5) and the other end in the adjacent empty cups (2 and 4). You should have paper towel strips connecting cup 1 to cup 2, cup 2 to cup 3, cup 3 to cup 4, and cup 4 to cup 5.

4. Watch the Water Walk: After a few minutes, watch as the water travels up the paper towels and into the empty cups, creating a rainbow effect!

   
   

The Science Behind It

This experiment beautifully demonstrates capillary action, a process that explains how liquids can move through narrow spaces:

1. Capillary Action: When the paper towels are placed in the water, they absorb it through capillary action, which occurs because of the adhesive forces between the water molecules and the fibers of the paper towel. The water molecules stick to the paper, allowing them to travel upwards against gravity.

2. Color Mixing: As the colored water moves into the empty cups, it creates a stunning visual display. The colors can also mix in cups 2 and 4, creating orange and green and completing the rainbow.

3. Hydrophilic Properties: Paper towels are hydrophilic, meaning they attract water. This property enables the water to rise through the paper towel fibers, demonstrating how plants also draw water from the soil through their roots and into their stems and leaves.

   
   

This experiment is a fun way to learn about the principles of capillary action and color mixing. Experiment with different colors or even try using different materials to see if the water moves faster or slower. Enjoy watching your rainbow grow!