Science Smarts: Make your own rainbow

By Patty Rooks on March 13, 2021.

As I look at the calendar today, I see that an important holiday is coming up next week – St. Patrick’s Day is fast approaching!

Whenever I think of this holiday, I think of Leprechaun’s and that pot of gold at the end of the rainbow – an old Irish tale I am sure my grandfather told many times! Of course as a child, what would be more appealing than getting to the end of the rainbow and collecting that pot of gold? Well, it is pretty hard to find a rainbow this time of the year but do not worry, we can make our own.

Let’s get started!

Remember to ask an adult before doing this experiment.

Materials

• Five clear glasses or jars (of the same size)

• Five different colours of food colouring

• Water

• Scissors

• Five sheets of paper towelling (Do not separate)

Procedure

• When you are ripping the paper towel off of the roll ensure you keep it in one long strip, this is very important.

• Fold the paper towel into one long narrow strip – I like to run it through my hands to tighten it up that way. Set aside.

• Fill each glass about 1/2 full of tap water.

• Add a different colour of food colouring to the water in each glass. Stir well.

• Place the glasses in a circle, each about 10 cm apart.

• Take one end of the paper towel strip and place it in the first glass, push it down in the middle, and make sure it is sitting in the water. Continue adding paper towel and pushing it down in each of the glasses until you are finished. It will look like a long snake of paper towel going from one glass to the other and so on.

• Observe. Be patient though as it make take a few minutes before anything happens.

What is going on?

Although you have a beautiful rainbow appearing before your eyes on these paper towels, I have to tell you that no, this experiment is not magic from the Leprechauns! It has to do with science, of course. As the coloured water from each glass travels up the paper towel, it is doing this by something known as capillary action. Simply put, capillary action is the ability of a fluid (the coloured water in this instance) to flow upward (through the paper towel) against gravity in a narrow space.

If you look closely at the water in each glass as it moves from one to the next, you will see the colours mixing – but this is a lesson for another day!!

Remember if your school is interested in doing a science fair this year, do not forget to connect with us at Praxis – we are here to help you – even virtually during the pandemic. Please keep reading here each week for more helpful ideas and even tips on Science Fair.

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.

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