Add 1/4 cup (60ml) of corn starch to 1/4 cup (60ml) of oil in a cup. Stir thoroughly.
Rub a balloon in your hair. Now slowly pour the oil-cornstarch mixture into another cup. As you are pouring, bring the charged balloon near the stream of fluid.
When you mixed the cornstarch and oil together you created a smart material called an electrorheological liquid. That is, a liquid that gets thicker in the presence of an electrical field. You created a field of electricity (called static electricity) by rubbing the wool against the plastic.
Cornstarch and oil do not conduct electricity. However, corn starch is dielectric. That is, when it is placed in an electric field, the molecules in it become charged. This makes them stick together.
In this experiment, the corn starch molecules stuck together and prevented both themselves and the oil molecules from flowing across each other – making the liquid thicker.