Materials Required
  • Two plastic bottle
  • Two balloons

How to do it

  • Take two plastic bottles.
  • Paint one bottle with black paint and the other with white.
  • Place the open end of one small balloon on the mouth of the white bottle. Take only small balloon to see the changes correctly.
  • And do the same for the black bottle.
  • Make sure the balloon forms an air tight seal with the bottle.
  • Now place both bottles in bright sunlight.
  • Within a few minutes, the you will notice the balloon on the black bottle will start to expand.
  • The balloon of the white bottle will remain limp.
  • Ask the child to touch the black bottle to notice that it is warm.
  • Then ask the child to touch and feel the white bottle which is cooler than the black bottle.

Explanation

  • The black bottle observes more heat than the white bottle and hence the air inside the black bottle expands due to the heat. Hence the pressure increases inside the bottle and causes the balloon to expand.