Materials Required
  • a flat bowl or a Saucer
  • Milk
  • Food color (four different colours)
  • Detergent

How to do it

  • Fill the saucer with the milk.
  • Add one of each food colour to the milk around the edge of the saucer.
  • Add one of detergent into the centre of the saucer.
  • Let your child observe the colours.
  • The colours swirl and zoom around the saucer.

Explanation

  • Milk stays together as one liquid because of surface tension. When detergent is added, it breaks the surface tension of the milk in one spot.
  • The pull of the surface tension from the milk at the edge of the saucer causes the milk in the centre to move to the outside, taking the colours along with it.
  • The colours keep moving until the detergent stops affecting the milk.
  • This will be a good colourful experiment for the kids.