What you need:
- tube or hose
- 2x glasses
What to do:
- Fill one of the glasses with water. You can add some food colouring to make the water easier to see if you like.
- Use the tube or hose like a straw and suck up some water from the full glass (but don’t think it).
- When the water gets to the top, put your finger over the top of the tube.
- Keeping your finger over the tube, put the top of the tube into the empty glass.
- Lift the full glass up and remove your finger from the tube – water will flow into the empty glass.
- Put the down glass down and lift the other one up, making sure the tube is submerged in the lower glass before you lift it up – water will now start to flow into the lower one.
What happens:
It was unclear exactly how a siphon works, but it is likely to do with air pressure, and perhaps a bit of gravity. Filling the tube with water to start causes a change in pressure, causing the water to flow from high pressure to low pressure. This allows the water to flow to the highest point of the tube. It then falls into the other glass because of gravity.
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