Exhibit: Static Dome
When you rub the dome, you charge the surface with electricity. You also charge up the sheepskin pad.
When you rub two things together, you remove some of the electrons from atoms on one and transfer them to the other. In the exhibit, electrons transfer from the wool fibres onto the surface of the perspex, so the wool is left positively charged and the perspex dome, with an excess of electrons, is negatively charged.
When the Perspex dome is negatively charged, all nearby atoms are distorted, that is, their positively charged nuclei are pulled away from the centre of the atoms towards the perspex dome. Each ball now behaves as if it has lots of positive charge on the side nearest the dome, so it is attracted to the dome. When you run your hand over the surface, you allow the excess electrons to leak away through your body. The beads will now fall back down or be attracted to other parts of the dome which are still charged.