Charge can build up on a surface and then jump as a visible spark. You rub a styrofoam plate with wool for about 45 seconds, building up charge on the surface. A pie pan — fitted with a pen body as a handle — sits on top of the plate. When you quickly touch the pie pan with your finger, a spark jumps to your fingertip. The device is called an electrophorus, and that spark is static electricity releasing its stored charge.

A buildup of charge on one object can affect a nearby conductor even without touching it. After building a simple circuit with a 9-volt battery, a transistor, and an LED, you charge a pen or comb by rubbing it and wave it close to an antenna wire. The circuit detects the invisible voltage field surrounding the charged object, and the LED responds — showing that static electricity acts at a distance.

A buildup of electric charge on a surface can pull lightweight objects through the air. You scatter Rice Krispies on a table, then balance a plexiglass plate on wooden blocks a few inches above them. Rub the top of the plexiglass with a wool sweater to build up a negative charge. The cereal pieces slowly stand on end, then leap upward to the plate. They stick briefly and fall back down — because opposite charges attract each other.

A huge buildup of charge can jump between objects as a spark, the same way lightning jumps between clouds and the ground. You rub styrofoam with a wool sock to build charge on the foam. Then you set an aluminum pie plate on top. When your finger gets close to the plate, a small spark jumps to your fingertip.

Rubbing different materials together builds up charge, but the amount may depend on the material's traits. You rub a balloon against natural-hair wigs of four different colors and then hold the balloon over small paper squares. Each color picks up nearly the same number of paper pieces, showing that hair color does not change how much charge builds up.