Allways the same side down- Electrical charges

This is a very simple demonstration, with an explanation beyond the obvious. This fully works using available materials. 

What we need:

• cooking oil,
• water,
• a small glass,
• cardboard,
• a charcoal,
• a puncher.

How to:

1. Fill half glass with water;
2. Fill the other half with oil;
3. Paint the cardboard with the charcoal, saturate the cardboard with the pencil as much as you can;
4. Punch little circles on the painted area;
5. Place the circles in the cup.

What happens?
The painted side always faces the oil.

Why?
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

1. Try other types of oil;
2. Try mixing salt or sugar in water;
3. Paint the cardboard with your colored pencils, or crayons ...

Record the observations, the falling speed of the balls and the number of times the balls fall into another position.

NOTE: You can only study one variable at a time, otherwise you will not be able to establish the cause / effect.

Et Voilá!
Electric charges at work
Enjoy!