Materials Required
  • A glass filled right up to the top with water
  • A piece of cardboard

How to do it

  • Do this experiment outside so that it will not spoil your home even if it is done wrong.
  • Place the cardboard on the top of the glass without leaving any gap.
  • Hold it tightly and now turn the glass upside down and then take your hand away from the cardboard.
  • The cardboard will not fall and hence the water will not.

What is learnt

Since the cup is full with water, the air pressure outside the glass is greater than the water pressure inside the glass. So the outer pressure hold the cardboard with the glass.