======Franklin’s Bells With Van de Graaff Generator======


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**Alternative titles:** Lightning Bells Demonstration
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====Summary====                   
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====Procedure====  
  - Suspend a small metal ball on a string so that it hangs freely between two unconnected metal plates.  
  - Ground one plate by touching it with your finger.  
  - Bring a Van de Graaff generator near the other plate to charge it positively.  
  - Observe as the ball is repelled from the positive plate and swings to strike the grounded plate.  
  - After contact, the ball becomes negatively charged and is attracted back toward the positive plate.  
  - The ball continues to shuttle between the two plates, ringing like Franklin’s original lightning bells.



====Links==== 
Van de Graaff 1 - Franklin's Bells - Robert Bass: 
{{youtube>yBNP8uWxVN8?}}\\

Franklin bell experiment with Van De Graaff generator - jcableman: 
{{youtube>hg7MMRJR5ew?}}\\

📄 Franklin's Bells - Classroom Physics Demos: [[https://demos.smu.ca/index.php/demos/e-n-m/171-franklin-s-bells]]\\


====Variations====
  * Use different sizes of spheres or plates to see how mass and surface area affect oscillations.
  * Demonstrate in a dark room to look for sparks during contact.




====Safety Precautions====
  * Do not touch the Van de Graaff generator or charged plate during operation.  
  * Keep sensitive electronics away from the setup to avoid electrostatic discharge damage.  
  * Ensure the suspended ball is securely attached so it cannot fly free.




====Questions to Consider====
  * Why does the ball continue to swing between the plates once started? (It is alternately charged positive and negative by contact with each plate, leading to attraction and repulsion.)  
  * What kind of energy conversion does this demonstrate? (Electrical energy is converted into mechanical motion.)  
  * How did Franklin use bells like this in the 1700s? (He connected them to lightning rods so they would ring during thunderstorms, signaling atmospheric electricity.)  
  * What modern devices use a similar principle of electric charging and discharging? (Electrostatic precipitators, capacitors, and some sensors.)