Questions on Van de Graaff Generator

[sniffer]

a few questions:

1. in van de graaff generator, is the sphere positive?

2. what will happen if we shorten the rubber band conveyor? to make the generator smaller and portable.

3. why does it maintain constant current when connected to a load? why doesn't the current decrease?

 

[Doc Al]

1. The rubber imparts a negative charge to the sphere.

2. I would imagine that the less rubber you have, the harder it will be to build up a charge.

3. Realize that you are imparting a charge to the sphere at some rate. When you connect the sphere to a load, that charge can discharge through the load creating a current. As long as you keep adding charge, why wouldn't the current remain the same (once a steady state is reached)?