# Van de graaff generator as a current source

• abdo799
In summary, if you ground the sphere, the generator will become a current source and you can measure the current.
abdo799
I know that van de graaff generator is a high voltage generator, i was wondering though if we can use it as a current source, if we get any resistor, connect the negative terminal to the generator "if the generator generates negative charge " then ground the positive terminal, then any charge that appears on the sphere will be immediately pulled to ground, creating a current, using simple formulae we can derive the current, is that feasible or not?

abdo799 said:
I know that van de graaff generator is a high voltage generator, i was wondering though if we can use it as a current source, if we get any resistor, connect the negative terminal to the generator "if the generator generates negative charge " then ground the positive terminal, then any charge that appears on the sphere will be immediately pulled to ground, creating a current, using simple formulae we can derive the current, is that feasible or not?
Sure, it's feasible as far as I can see but it is a HUGE waste of electricity to do that since the amount of current you'll get is tiny vs the amount you have to use to get it.

Yea i know, i calculated it, and the efficiency was extremely low

Just wanted to know if it would work, going to use it to measure how much time does my generator need to reach maximum voltage

abdo799 said:
Just wanted to know if it would work, going to use it to measure how much time does my generator need to reach maximum voltage
I don't get how you could do that.

My plan is by grounding the generator and measuring the current in the wires i can use it to know the time to reach the maximum voltage, can't write the formula now because i am using the mobile app

abdo799 said:
My plan is by grounding the generator and measuring the current in the wires i can use it to know the time to reach the maximum voltage, can't write the formula now because i am using the mobile app
Assuming I=const the formula is simply t=Vmax⋅C/I

I don't know yet if I is constant, but theoretically, it should be

abdo799 said:
My plan is by grounding the generator and measuring the current in the wires i can use it to know the time to reach the maximum voltage, can't write the formula now because i am using the mobile app
I still don't get it. If you ground the wires, or run the output of the generator through a resistor, you won't GET any voltage on the sphere. I think you must be talking about something that I'm not following.

That's the whole idea, i don't need any voltage, by grounding the sphere, the generator became a current source, so i measure the current in the wire, or my case i will connect a high resistance and measure the voltage across it because the current will be low and hard to measure.
The maximum voltage of a van de graaff generator is 3*10^6*radius(in meter), and the voltage on the sphere is kQ/r where K is coulomb's constant
Q=I*t and we're done

## 1. How does a Van de Graaff generator work as a current source?

The Van de Graaff generator works by using a motor to continuously build up a high voltage charge on a hollow metal sphere. This charge is then transferred to a metal terminal, creating a strong electric field between the two. When a conductor is brought close to the terminal, electrons will flow from the terminal to the conductor, creating a current.

## 2. Can a Van de Graaff generator be used as a reliable current source?

While a Van de Graaff generator can produce high voltage and high current, it is not considered a reliable current source. This is because the current it produces is highly variable and depends on factors such as the humidity and temperature of the environment, as well as the distance between the terminal and the conductor.

## 3. How much current can a Van de Graaff generator produce?

The amount of current produced by a Van de Graaff generator depends on the size and design of the generator, as well as the conditions in the environment. It can range from a few microamps to several milliamps. However, it is not typically used as a primary current source and is better suited for experiments and demonstrations.

## 4. Is it safe to touch a Van de Graaff generator while it is producing current?

It is generally safe to touch the metal terminal of a Van de Graaff generator while it is producing current. However, it is important to note that the high voltage charge can cause a shock, and the current can be strong enough to disrupt the normal functioning of the body. It is always recommended to use caution and follow proper safety protocols when working with high voltage equipment.

## 5. What are the applications of a Van de Graaff generator as a current source?

A Van de Graaff generator can be used in a variety of applications, including scientific research, education, and industry. It is commonly used to demonstrate the principles of electricity and to conduct experiments in electrostatics. It can also be used in particle accelerators and in the production of x-rays. However, due to its limitations as a current source, it is not typically used for practical or commercial purposes.

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