Materials Required:
- Funnel
- Big glass bowl
- Water
Procedure:
- Set a funnel, small side up, on a counter top; then set a big glass bowl next to it. Notice how high the tip of the funnel extends. Fill up the glass bowl with water to a level just below this point.
- Hold the funnel between your thumb and middle finger, keeping your index finger over the small opening. Push the funnel into the water until it touches the bottom of the bowl. Raise your index finger slightly. You will feel a puff of air blown
at your finger.
This is what happens:
When you are holding the funnel with your finger over the tip, a quantity of air is inside the device. As you press the funnel to the bottom of the bowl, this air remains trapped inside the funnel; your finger blocks it from the top and the water blocks it from below. When you remove your finger, the pressure of the water pushes against the air inside the funnel and forces it out through the small hole. If you used a glass funnel, you could see the water level rise inside the funnel as the puff of air hits your finger!
