Let's Discover: Spray It, Don't Say It!

 

 
On October 12th, Discovery Centre took part in a Canada-wide attempt at a new Guinness World Record for the largest practical science lesson held simultaneously at multiple venues. One of the components of that lesson on Bernoulli’s principle is a great one to try at home, so we present to you The Atomizer!
 
For this experiment, you will need some drinking straws, scissors and a cup of water. Be warned: the title is accurate; there will definitely be a spray of water so you’ll want to do this in an appropriate space - like outside or in the bathroom.
 
First, cut a straw so that you have lengths of 6 cm and 10 cm – depending on your straws, you may need to use two. Place the short length of straw into your container of water so that a portion of it is sticking out over the rim and so that you can hold your vessel and your straw in place at once (you’ll need a free hand for the next part). Now, take your longer straw and aim the end so that it passes flat across the top of your short straw (the partly-immersed one); you are going to blow through the big straw, across the top of the small one. If you adjust the angle at which the air passes over the small straw, you will find a point at which the jet of air also begins to spray a large, fine mist of water!
 
 
Daniel Bernoulli discovered in the 1700’s that a fast-flowing stream of air is lower pressure than its surroundings; this makes the ambient air pressure (pushing down on everything) push the water down into the container and up into the straw to fill the low-pressure area –a jet of air, producing a mist. This is how traditional spray bottles (“atomizers”) for perfume and cologne work, as well as how airbrushes work. For some extra fun you can use dyed water to paint a picture using your contraption!
 
If participating in special events like the Guinness World Record-breaking session sounds like fun we’ve got lots of great upcoming events like the Rubik’s Cube Speed Challenge Event on October 20th and our 2nd Annual Spooktacular Science Party on October 27th! Be sure to keep a close eye on our Twitter account (@DiscoveryCntr) and our Facebook page for details on these and other great events and activities here at the Centre!
 
 
For more great things to discover - visit the Discovery Centre on Barrington Street in Halifax, check out their website or join them on facebook.
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