Re: Van de Graaff

[paulus@physics.otago.ac.nz (Paul Yates)]

> I should add here, that when the volunteer comes up front to do the demo,
> have the VDG globe discharged and the VDG turned off.  Have the subject place
> a hand on the globe _before_ turning it on.  This reduces the pain
> to the volunteer subject.  After the hair raising demo, turn the VDG
> off, and then have the subject release the globe first, then step down
> after releasing the globe.  Again, this reduces the pain to the subject.

> - Roger Key

Another way to discharge is to get the subject to hold a set of keys
"splayed out" in open air, or close to an earthed conductor - this is a
painless approach. Also, while the subject is still touching the dome
slowly approach them with keys in hand. If their hair is standing up you
can collapse one side! The subject can feel the effect of the discharge
through clothes etc while the keys are about half a meter away.

For the brave to try: while standing on the insulating platform slowly
bring a bunch of keys near the dome while the VDG is running, until the
keys touch the dome. You can painlessly acquire several hundred thousand
volts this way! Don't do it too quickly tho'...



Paul Yates                   paulus@physics.otago.ac.nz