Today we will use black pepper powder.
What we need:
- black pepper powder,
- wool cloth,
- plastic fork or spoon,
- Mix some pepper and salt in the plate,
- Mix well, use the fork to help you;
- Ask your restless to separate the salt from the pepper, humm... tricky uh?;
- Rub the fork in the cloth for 30-60sec;
- Approach the fork and the plate, keep the fork 2,5cm away from the plate.
The pepper jumps to the fork, leaving salt behind
When you rub the fork with the cloth it becomes negatively charged, pepper is positively charged. That means, when you approach the fork the pepper is attracted to it, and "jumps".
The salt is also negatively charged but is slightly heavier and it doesn't jump so easily. However, if you don't keep fork distance the salt will eventually jumps, thats because the electrical attraction overcomes the weight.
See the movie:
You can learn more about this here.