Static electricity. Strips of paper that have been electrically charged by a Van de Graaff generator, a device that generates static electricity. Charge accumulates on the metal dome and is transferred to the paper. When uncharged, the strips of paper hang downwards under gravity, but when they are electrically charged they repel each other and move upwards and apart (as is seen here). This is possible because the electrical force is stronger than gravity. The two opposing types of electrical charge (positive and negative) usually cancel out, but excess charge (as here), clearly demonstrates the greater strength of the electrical force.