Van de graaff generator as a current source

[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?

 

[phinds]

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.

 

[abdo799]

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

 

[abdo799]

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

 

[phinds]

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.

 

[abdo799]

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

 

[zoki85]

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

 

[abdo799]

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

 

[phinds]

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.

 

[abdo799]

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