The field of electrostatics deals with electrical charge that is stationary (not moving). In contrast, we call moving electrical charge, electricity. Static means not changing or moving. The gold-foil electroscope pictured to the right uses a very thin and very light piece of gold foil to measure electrostatic charge. More charge moves the foil farther away from the metal post it is attached to. When one substance rubs against another, charge will be transferred because two different substances have different affinities (attraction) for electrons. The greater the difference, the more charge will be created. Both the rod and the cloth become charged, but with opposite charges. In this activity, you will see each experiment investigates one cloth with three rods. Looking at the deflections of the electroscope for each cloth with the different rods, you will observe if one cloth produces more electrostatic charge than the others. You can also compare the rods and find out which produces the most charge no matter which cloth is doing the rubbing. Here are tables of the rods and cloths used in the experiments.