# Van Der Graaff generator question.

• templedog
In summary: You can charge a ping pong ball either by rubbing it with fur or by putting the ground wire in one through a small hole in it.
templedog
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?

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?

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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?

## 1. What is a Van Der Graaff generator?

A Van Der Graaff generator is an electrostatic generator that uses a moving belt to accumulate electric charge on a large metal sphere. It is commonly used in physics demonstrations to create high voltage electricity.

## 2. How does a Van Der Graaff generator work?

The generator works by using a moving belt to continuously transfer charge from a lower voltage source to a larger metal sphere, creating a build-up of static electricity. This charge can then be released through a discharge wand or through sparks between the sphere and another object.

## 3. What are the main uses of a Van Der Graaff generator?

A Van Der Graaff generator is mainly used for educational purposes, such as physics demonstrations and experiments. It is also used in particle accelerators and in some medical procedures, such as radiation therapy.

## 4. Is a Van Der Graaff generator safe to use?

When used properly, a Van Der Graaff generator is generally safe. However, it can produce high voltage electricity and should only be operated by trained professionals. It is important to follow all safety precautions and instructions when using a Van Der Graaff generator.

## 5. Can a Van Der Graaff generator produce unlimited electricity?

No, a Van Der Graaff generator can only produce a finite amount of electricity. The amount of electricity it can produce depends on factors such as the materials used, the size of the sphere, and the speed of the belt. It cannot produce unlimited electricity as it relies on the transfer of charge from a lower voltage source.

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