Bouncing Mylar Balloon

Discharges from the Van de Graaff are painful and startling. Keep students at least 2 meters away. Individuals with pacemakers should avoid proximity. Always discharge the dome to ground before touching.

Static discharges can damage nearby electronics. Warn students to keep laptops and phones away from the demonstration area.

Purpose

A metallized Mylar balloon oscillates between a Van de Graaff generator and a grounded sphere, illustrating charging by induction, charge transfer by conduction, and electrostatic repulsion. Students see the full charge cycle: polarization of a neutral conductor, contact charging, and grounding.

Person holding a two-meter stick with gold Mylar balloon on a string, motion-blurred as it swings between a smaller grounded sphere on a stand (left) and the larger Van de Graaff generator sphere (right)

Gold Mylar balloon resting on the lecture bench between the grounded sphere on stand (left) and the Van de Graaff generator (right), with two-meter stick lying on the bench

Figure 1: The Mylar balloon in motion between the grounded sphere (left) and Van de Graaff generator (right). The motion blur captures the balloon mid-oscillation.

Figure 2: Setup showing the Mylar balloon, grounded sphere (left), Van de Graaff generator (right), and two-meter stick used for spacing reference.

Danger: High Voltage Electrical Hazard

Warning: Static Discharge Precaution

Purpose

Safety Warnings

Danger: High Voltage Electrical Hazard

Warning: Static Discharge Precaution

Purpose