Diagram illustrating a Van de Graaff generator and a suspended pith ball, showing the deflection angle and distance for calculating electrostatic force.
Diagram showing a Van de Graaff generator with a pith ball suspended by an insulating thread, deflected at a 2.9° angle. The generator is labeled, and the distance from the generator to the pith ball is 30.0 cm. The pith ball is shown with a label "Pith ball" and a dashed line indicating the vertical reference.