Van Der Graaff generator question.

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Discussion Overview

The discussion revolves around the operation and charging mechanisms of Van de Graaff generators, specifically focusing on the types of charges generated, the materials involved, and methods for charging different objects. Participants explore theoretical and practical aspects of charging, including the effects of size and material on charge accumulation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether a ball placed on a negatively charged wand will acquire the same charge as the aluminum sphere or an opposite charge.
  • Another participant inquires if a Van de Graaff generator can be designed to charge a plastic ball instead of metals and expresses uncertainty about the wand's functionality.
  • It is noted that while most Van de Graaff generators charge positively, they can also be configured to charge negatively, and that plastic objects are less easily charged due to their non-conductive nature.
  • A participant asks if a hollow rubber/plastic/teflon ball can be charged negatively and whether it would deliver a shock upon contact, questioning the necessity of grounding the metal object or attaching it to the opposite brush.
  • One response clarifies that attaching to the opposite brush can work, and that a rubber ball would not deliver a shock unless it is a good conductor, suggesting a method to make it conductive by spraying it with copper or graphite.
  • A participant wonders if painting a stainless steel gazing ball would still allow it to spark and questions whether the size of the aluminum sphere affects the strength of the negative charge.
  • Another participant confirms that painting the ball will not affect its functionality and explains that a larger aluminum sphere can store more positive charge, but the relationship between the negative charge and the grounded object is influenced by various factors, including distance.
  • A final inquiry is made about charging a ping pong ball negatively through a small hole with a ground wire versus rubbing it with fur, questioning which method is more effective.

Areas of Agreement / Disagreement

Participants express various viewpoints on the charging mechanisms and configurations of Van de Graaff generators, with no clear consensus on the effectiveness of different methods or the implications of size and material on charge strength.

Contextual Notes

Some assumptions about the behavior of charges and the effectiveness of different materials in charging processes remain unaddressed, and the discussion includes unresolved questions about the best methods for charging specific objects.

templedog
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The aluminum sphere on it is generating a positive charge and the wand a negative. If I put a ball on the wand, will it charge the same way the big one does? Just opposite charge?

anyone know about this thing?
 
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I guess what I'm talking about. Can you make a Van Der Graaff that works in the opposite? One that charges a plastic ball instead of aluminum or steel? but does it already do that? The wand? I'm pretty much incompetent when it comes to this.
 
Most Van de Graaff generators charge positive but they can also be build so that they will charge negative. When a grounded metal object is close to a positively charged VDG it will become negatively charged. Plastic objects don't conduct electricity and so they can't be charged up that easily. But you can charge a plastic ball by rubbing it.
 
Can I take a rubber/plastic/teflon ball that is hollow, and charge it negative? If I touch it would it zap me?does the metal object have to be grounded? or just attatched to the opposite brush? the one at the bottom?
 
Last edited:
Attaching it to the opposite brush will work too.
A rubber ball can not zap you. To get a shock all the electric charge in the ball would have to flow into you within a tiny fraction of a second. That can only happen when the ball is a good conductor.
But you could spray the ball with copper or graphite spray to make it conductive.
 
If I spray paint a stainless steel gazing ball, will it still give a spark?

Does the negative charge get stronger if the aluminum sphere is larger? or does that matter?
 
Last edited:
Sure, you can paint it. It will still work.
When the aluminum sphere is bigger it will store more positive charge. Whether the negative charge on the grounded object changes depends on different factors.
As long as the grounded object is not too close to the aluminum sphere it's charge is approximately proportional to (radius of the aluminum sphere) / (distance from the aluminum sphere).
If it's very close to the sphere it gets more complicated and the amount of charge depends mostly on the distance since the distance determines how high the voltage can be before a spark jumps over.
 
Last edited:
Can i charge a ping pong ball with a negative charge by putting the ground wire in one through a small hole in it?or only by rubbing it with fur? or both? If both, I wonder which is best?
 

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