What we need:
- cooking oil,
- a small glass,
- a charcoal,
- a puncher.
- Fill half glass with water;
- Fill the other half with oil;
- Paint the cardboard with the charcoal, saturate the cardboard with the pencil as much as you can;
- Punch little circles on the painted area;
- Place the circles in the cup.
The painted side always faces the oil.
Graphite is a good conductor, and has negative polarity. The polarity of the graphite repels water so that the painted face is always facing the oil.
Transform this demonstration in an experiment
- Try other types of oil;
- Try mixing salt or sugar in water;
- Paint the cardboard with your colored pencils, or crayons ...
NOTE: You can only study one variable at a time, otherwise you will not be able to establish the cause / effect.
Electric charges at work