Praxis: Create a rainbow without the rain
By Patty Rooks on March 14, 2020.
praxis@praxismh.ca@PraxisMedHat It is that time of the year – St. Patrick’s Day is fast approaching. We all know that those sneaky little Leprechauns come out this time of the year and hide their treasures in those elusive pots of gold at the end of the lucky rainbow. I don’t know about you, but I could use a little good luck these days! Unfortunately, I never have any luck hunting down this elusive rainbow outside, so I am going to make my own rainbow inside with a little help from science. Let’s get started! *Remember to ask an adult before doing this experiment. Materials – six clear glasses – water – measuring cup – six different containers of food colouring – paper towel – scissors Procedure 1. Place all of your glasses in a row on a flat sturdy surface. 2. Measure 125 mL (1/2 cup) of water and pour into one of the glasses. 3. Repeat for all six glasses. 4. Add a couple of drops of food colouring to one glass. Mix in well. You want a nice bright colour. 5. Repeat with a different colour for each of the remaining glasses. 6. Cut a sheet of paper towel in half. Fold it in half lengthwise and again. You want to have a nice long strip of paper towel. 7. Place one half of the paper towel in one glass and the other side of the paper towel in the glass beside it. 8. Repeat with the remaining glasses. 9. Observe what is happening. What is going on? This experiment is often called “Walking Water” because the water literally walks from one glass to another as you should have been able to see from the paper towel. It kind of looks like magic as the water is moving up the paper towel from one glass to another. In reality, the water is moving due to capillary action. There are adhesive forces between the water and paper towel that are much stronger than the cohesive forces inside of the water. As a result, the water is able to travel up the paper towel out of one glass and right into the next one and so on. I hope you enjoyed the rainbow of colours you were able to make! NOTICE: Due to concerns surrounding COVID-19 the Regional Science Fair set for March 21 has been cancelled. Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: #12 826 11 Street S. E., Medicine Hat, Alberta, T1A 1T7 Phone: 403.527.5365, email: praxis@praxismh.ca. 25-24
