Van de Graaff Levitating Foil

Thin strips of aluminum foil can be levitated and made to spin near the charged dome of a Van de Graaff generator. The electrostatic field induces a dipole in the strip, while ionic wind from the generator provides lift and rotation, creating a dramatic and attention-getting demonstration.

1. Cut strips of aluminum foil about 50 mm long, 2.5 mm wide, and 0.02 mm thick.
2. Charge a Van de Graaff generator so that its dome is strongly electrified.
3. Bring a foil strip near the dome, aligned with the electric field lines.
4. Observe as the foil strip levitates at a distance of about 15 cm from the dome.
5. The strip spins due to a combination of induced dipole attraction and ionic wind streaming from the dome.
6. Try releasing several strips around the dome to see multiple spinners levitate simultaneously.

Electrostatic levitation using Van de Graaff generator - dizekat:

van der Graaff levitating aluminium foil - PhysicsExperiments.org:

• Use different sizes, shapes, or twists of foil strips to compare rotation speeds and stability.

• Do not touch the Van de Graaff dome while it is operating.
• Keep electronic devices away from the generator to avoid damage from static discharge.
• Ensure foil strips are lightweight and free of sharp edges.

• Why do the foil strips first attract to the dome and then stabilize at a distance? (Electrostatic attraction competes with repulsion from ionic wind, producing balance.)
• What causes the strips to spin? (Slight twists in the foil interact with the ionic wind, creating torque.)
• How is this related to the behavior of other lightweight objects in strong electric fields, like the “Orbiting Foil” demonstration?
• What role does the electric dipole moment play in the attraction of the foil strips?