The aim of this science fair experiment is to demonstrate that static charge exists with the help of rice krispies.
1. A plate of rice krispies.
2. A bar of thermoplastic.
3. A block of wood so that the thermoplastic can be placed 1-3 inches above the table.
4. Some wool preferably a sweater.
1. Place the plate full of rice krispies on the table.
2. Take the wooden block or for that matter any non conductive block and balance the thermoplastic bar on the block right above the plate of krispies.
3. Then rub the wool on the thermoplastic, vigorously. Leave it as such. After sometime we see that the krispies would stand on its end and then ‘jump’ from the table to the thermoplastic and then drop back to the plate on which it was placed.
This is the result of buildup of static charge. When we rub the wool on the thermoplastic it gets charged negatively. This in turn polarizes the rice krispies which is right below the charged thermoplastic. The krispies gets positively charge (polarization results in accumulation of opposite charges). And s we all know that unlike charges attracts. So as the polarization slowly takes effect, the charge difference keeps on increasing. As a result the krispies first stands on its end and later when the charge difference is sufficient the krispies jumps and sticks to the thermoplastic bar. As they both come in contact their respective charge neutralizes and the force of attraction vanishes. Then gravity comes into picture which pulls the krispies down as the static charge vanishes. The neutral krispies fall back to the plate.