Heated to a Crisp (Super Science Experiments)

You will need:

1. Microwave oven
2. An empty wafer packet (should be shiny)

Create sparks in your kitchen with this simple experiment. But ask an adult to perform this experiment for you.

INSTRUCTIONS

1. Remember to ask an adult to do this experiment for you.
2. Take your empty wafer packet and place it in the microwave oven.
3. Switch on and start the microwave with the packet inside for exactly 4 seconds. Do not heat the packet for more than 4 seconds as it can damage the microwave.
4. Wait for a minute after you have switched off the microwave, and then gently remove the wafer packet from the microwave. It would have shrunk and got harder than usual.

RESULT

The shiny wafer packet is made of aluminium foil packed between two layers of plastic. This is done so as to keep wafers fresh and ‘oxygen-proof’. Due to the aluminium foil and layers of plastic, 2 things happen. Firstly, the packet shrinks. This is because of the long polymer molecules in the plastic, which are straight, but when heated they begin to vibrate making them bend and wriggle, leading to the plastic becoming stiffer and shorter. Secondly, the microwave is made up of electromagnetic waves, which create electricity and current when they hit a conductor of electricity. In this case, the aluminium foil, which comes into contact with the air after the plastic around it, begins to shrink. As soon as a current begins to flow through the foil, it builds up wherever there are cracks in the foil, jumping through the air. It is a bad conductor for a current, thus creating sparks.