Demos: 2C-05 Atomizer Model
A straw is cut in half and one part is placed in a beaker of water, as illustrated. The other part is used to blow a stream of air over the opening of the immersed straw. Water is pulled up the straw and blown into the air in small droplets, simulating an atomizer.
Directions: Although this is not a difficult demonstration, try practicing a little beforehand to get the technique down. Hold the immersed straw against the side of the beaker with your finger and using other straw blow firmly just over the edge of the vertical straw. With a little practice, you can create a considerable spray.
Suggestions for Presentation: Start out by saying, If any of you is caught doing this demonstration at McDonalds with a Coke, Ill swear you didnt see it here! Then ask if anyone knows what an atomizer is (they arent used much anymore). Ask what happens to the pressure at the end of the immersed straw if a rapidly moving stream of air is directed past it. Point out that Bernoulli explains the water being drawn up into the straw, but just plain impact (transfer of momentum) is involved in the liquid being sprayed into the air.
Applications: Atomizers, carburetors.