======Van de Graaff and Soap Bubbles======


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**Alternative titles:** Charged Bubbles Demonstration
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====Summary====                   
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====Procedure====  
  - Set up a Van de Graaff generator in a space where bubbles can drift freely.  
  - Use a soap bubble gun (or simply blow bubbles) so that they fall from above toward the charged dome.  
  - Observe: bubbles are initially attracted and move closer to the generator.  
  - When one bubble touches and pops on the dome, droplets become charged and spread to other bubbles, charging them.  
  - The remaining bubbles are now repelled by the generator and begin moving away.  
  - Record the experiment on video, play back in slow motion, and ask students to refine their observations and explanations.



====Links==== 
Van de Graaff generator and bubbles - Science experiment - Coolphysicsvideos Physics: 
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Static Electricity and Bubbles! - Jefferson Lab: 
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📄 Does Van de Graaff not like a shower? - Wouter Spaan: [[https://interactivetextbooks.tudelft.nl/showthephysics/demos/demo10/demo10.html]]\\


====Variations====
  * Slow the video to highlight the moment bubbles switch from attraction to repulsion.  
  * Try adding light paper pieces along with bubbles for comparison (paper is only attracted, not repelled).  
  * Replace bubbles with mist or smoke to show differences in behavior.



====Safety Precautions====
  * Do not touch the Van de Graaff generator while it is running.  
  * Keep liquids (bubble solution) away from electrical equipment.  
  * Ensure the generator is properly grounded when turned off.




====Questions to Consider====
  * Why are bubbles first attracted to the generator but later repelled? (They are neutral at first and attracted by induction; later they acquire charge from droplets of popped bubbles, leading to repulsion.)  
  * What role does induction play in the initial attraction? (Water molecules in the bubble wall align with the electric field, causing a net force toward the charged sphere.)  
  * Why do some bubbles move away from each other? (They carry like charges and repel one another.)  
  * How is this demonstration an example of scientific inquiry? (Students form hypotheses, make predictions, observe carefully, and test which explanation best fits the evidence.)