Electric Whirl - Physics Demonstrations - Electric Whirl | Physics Undergraduate Labs

Van de Graaff generators produce voltages exceeding 100 kV. While current is limited to microamperes (making it generally safe), the discharge can be startling and painful. Keep hands away from the dome during operation. Individuals with pacemakers or other electronic medical devices should not approach within 1 meter. Discharge the dome by grounding it with a discharge wand before handling.

Purpose

Corona discharge at the sharp tips of a wire whirl placed on a Van de Graaff generator produces ionic wind that drives mechanical rotation. Students see how concentrated electric fields at points of high curvature cause air ionization and momentum transfer.

Electric whirl at rest on the Van de Graaff dome, showing bent wire arms on a vertical pivot shaft

Electric whirl spinning on the Van de Graaff dome, with motion blur visible from rapid rotation

Figure 1: The electric whirl at rest on the Van de Graaff dome. The bent wire arms create corona discharge at their sharp tips when the generator is charged.

Figure 2: The whirl spinning under ionic wind propulsion. Rotation direction depends on the bend direction of the wire arms.

Electric Whirl

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Safety Warnings

Danger: High Voltage Hazard

Purpose