======Van de Graaff Levitating Foil======


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**Alternative titles:** Electrostatic Spinning Strips
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====Summary====                   
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====Procedure====  
  - Cut strips of aluminum foil about 50 mm long, 2.5 mm wide, and 0.02 mm thick.  
  - Charge a Van de Graaff generator so that its dome is strongly electrified.  
  - Bring a foil strip near the dome, aligned with the electric field lines.  
  - Observe as the foil strip levitates at a distance of about 15 cm from the dome.  
  - The strip spins due to a combination of induced dipole attraction and ionic wind streaming from the dome.  
  - Try releasing several strips around the dome to see multiple spinners levitate simultaneously.



====Links==== 
Electrostatic levitation using Van de Graaff generator - dizekat: 
{{youtube>-LcGVbTwLvA?}}\\

van der Graaff levitating aluminium foil - PhysicsExperiments.org: 
{{youtube>KQ008IGqG5I?}}\\


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



====Safety Precautions====
  * 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.




====Questions to Consider====
  * 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?