How can you make a “walking rainbow”? And why does it “walk”? Let’s answer these questions by experimenting!
Let’s gather our supplies!
Supplies:
Food coloring-red, yellow, blue
6 Paper towels pieces cut to fit in each section
Water
3 Popsicle sticks for stirring
a tray with 6 sections (pictured)
Directions:
1️⃣ Squeeze one drop of food coloring in every other section of the tray. Start with red, skip one, then yellow, skip one, then blue, skip one.
2️⃣ Fill the compartment up to 2/3 of water where each drop of food coloring is. Mix with a separate popsicle stick for each color.
3️⃣ Cut paper towels into rectangles that are long enough to fit one piece into two compartments. Put one half of the rectangular paper towel piece in red, and the other in the empty section. Next put the second paper towel sheet in the empty section and the other half in the yellow. Repeat until finished.
4️⃣ Watch the water as it travels up and begins to mix. After a few hours, the primary colors will have mixed in the empty sections, producing the secondary colors and therefore a rainbow!
So what causes this walking rainbow effect?
Capillary Action! Capillary action occurs when adhesion is more than cohesion. Adhesion is water/food dye that climbs up the paper towel cellulose and cohesion is when water clings to water. Eventually due to saturation & gravity, this process will reverse and a new color will be in the once empty space.
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*Adult Supervision Is Required For All Activities*