Why do Van de Graaff generators produce such low current?

[supernova88]

I'm currently in a program to be a physics teacher and for an upcoming mock lesson plan I am going to show the scene from Jurassic Park where the kid gets blasted off the electric fence and talk about if it is realistic. To supplement my discussion I'll be using a Van de Graaff generator to differentiate voltage and current. Obviously I want to deter people from sticking their fingers in electric sockets, so I'm hoping someone could remind me what it is about Van de Graaff generators (and electric fences) that keeps their current to a few microamps so I can use it as a concrete comparison to more dangerous electric wires and devices.

Also, I know if you're insulated (i.e. midair) and touching a wire you don't complete a circuit and should be fine, but if the kid's holding onto an uncharged wire and it powers up (10,000 volts, and I assume a bit more amperage than a cattle fence) would it still have no effect?

 

[.Scott]

Van de Graaff generators are not "inherently" safe. When they are safe, it is by design.
Also, when safety exists, it is as much a matter of duration as it is current.

See here:
http://www.nuffieldfoundation.org/practical-physics/van-de-graaff-generator-safety