Electric Force Experiment

5 Glass Rods, 5 Nylon rods, 1 Polystyrene rod, Pith ball pair,2 Aluminum foil covered ping pong balls on strings, 8 white ping pong balls, 4 Acetate (red), 1 Piece of Teflon, 6 Silk Smooth Cloths, and 3 Cotton Cloths Taylor 102, Demonstration Cabinet III Shelf B