Balloon on a Wall
Purpose
A charged balloon sticks to a neutral wall through electrostatic induction. The electrostatic attraction between the balloon's charge and the induced surface charge in the wall easily overcomes the gravitational force on a fraction-of-a-gram balloon — a vivid demonstration that electromagnetic forces are far stronger than gravity.
Figure 1:
Charged balloons adhering to a wooden surface and a chalkboard through electrostatic induction.