What you need:
Piece of card or postcard
Food coloring (optional, this is to make the experiment easy to see)
What Do You Need To Do?
- Put water in the jug and add some food coloring, if desired.
- Pour the water into the glass all the way to the top.
- Put the card on the glass and holding your hand over it quickly turns the glass upside down.
- Now remove your hand. What do you see?
The card will look as though it is “holding” the water in the glass!
How did it happen?
It is the pressures on the card from the water and the air on the other side of it!
The pressure of the water in the glass on the piece of card is much less than the pressure of air below the piece of card. This keeps the postcard firmly pressed on the glass so that no water can flow out.
Let’s get your child to try the trick herself!
Your child will be excited to learn about the science of air and water pressure, the logic behind this magic.
You can ask your child repeated the experiment with an empty glass and a glass that is half full of water. Ask your child to try it out and to explain the science behind her / his results.
Watch the demonstration: