First clue: everything is built from tiny bits, and some carry a hidden charge. There are two kinds — blue and orange. You can't see them, but they're in everything.
Rub two things together and tiny blue charges scrape off one and pile onto the other.
But why does that make it stick? A blue charge and an orange charge pull toward each other across empty space — no string needed.
Hold the balloon beside the wall. Drag to add blue charges. Watch the nearby orange charges shift toward it.
Held at the same height: more charge makes a stronger sideways pull.
One more clue.
Metal lets charge move. Connect this charged metal bead to the ground. Watch its extra blue charges leave.
Four extra charges on the bead.
Next: in our model, grounded metal touches the balloon’s whole rubbed patch. Then try the wall again.
You just saw: more charge means a stronger pull.
Press the balloon’s whole rubbed patch against a grounded metal pole. Try the wall again — does it still stick?
Touch metal. Return. Let go.
