A plexiglass rod rubbed with fur picks up a positive electric charge, while a rubber rod rubbed with fur picks up a negative electric charge. When either rod is brought in contact with hanging tinsel, the tinsel becomes charged and flares out. The other rod, however, will now attract the tinsel. Touching the tinsel with your hand discharges it.   These electrostatic forces can also be seen with a conducting balloon. Touching a charged rod to the balloon transfers charge, causing the balloon to be repelled away from the rod. The ancient Greeks noticed this phenomenon when rubbing pieces of amber (which pick up a negative electric charge, like our rubber rod). The word "electricity" is based on the Greek name for amber: "elektron."