electrostatics- human chain

[Ocean Breeze]

Anyone remember how to use the vandergraph generator with the human chain of students , holding hands and their hair stands on end(and a few get zapped)

Not working.. have I forgotten something?

[Slartibartfast]

Plenty of zap from the generator I suppose? Incidently, we're not to conduct this prac in this fashion in NSW Dept. of Ed. schools for risk of inducing cardiac arrest or seizures in students. 2 Workcover NSW cases last year. Sorry. Plenty of other cool pracs available though! i.e:

Warning:
Although the Van der Graaf generator can be used for many different fun and exciting demonstrations it has the possibility to hurt someone. No one with possible heart problems or with a pacemaker should ever use it. It should not be used in close proximity to another conductor or computers as it may ark to them. Clear off the table before using. When turning the generator off insulate yourself from the switch as you may get shocked. Remember to ground everything after completing a demonstration. Have fun but be careful.


Sparking:
Start Van der Graaf
Bring hand next to Van der Graaf it will ark to your hand. MAKE SURE THAT THE VAN DER GRAAF HASN’T BEEN ON VERY LONG!!!!
Use a ground wire to have the charge jump from the Van der Graaf to the groundwire.
Turn it off.

Bubbles:
Start Van der Graaf
Have someone blow bubbles at the generator
The bubbles are originally neutral and are attracted to a charged object.
When the first bubble hits the generator the popping releases electrons into the air and charges the rest of the bubbles.
The bubbles and the generator are then the same sign and repelled.
If the bubbles are not popping you can try to levitate a bubble under your hand. The charged bubble is attracted to your uncharged hand.
Turn it off.
Ground the generator.

Pie pans:
Place a stack of the cheap aluminum pie pans on top of the van der graaf while it is turned off and discharged.
Start the van der graaf
The electrons in the generator are transferred to the pie pans and thus repel each other.
Turn it off.
Ground the generator.

Packing Peanuts:
Place a pie pan full of packing peanuts on top of the generator while it is turned off and discharged.
Start the van der graaf
The electrons in the generator are transferred to the peanuts and thus repel each other.
Turn it off.
Ground the generator.



Sorry, I know this doesn't answer you question exactly but guidlines have changed. We had a great science teacher while I was in year 9 & 10 and we had this prac done to us. Great fun! Threw us across the room!!!

[Ocean Breeze]

Thanks for that Richard. I am glad that the DET dont do that prac any more.. it always made me a little uncomfortable. So now I have a good reason to advise that its not to be done.
I will definately try these other pracs

[ellice]

Hi Rainbow Sky,
I bought a new belt this year, as the other was a bit stretched. Then I gave the Van der Graff a good polish. Works a beauty now. Had to post a warning for users !!

[Ian]

We do the pie plate one that Richard mentioned. We also bought a cheep "Party Wig" from a $2 Shop, which our Van de Graaf wears often to show the hair raising effect.

We have used a small LED to make a human circuit (using an ordinary 12 volt lab power supply). Because the voltage is very low, (less than 12 volts) and the current is also very tiny, (only a few milliamps) there is no sensation of electricity, but the LED will light and go out if the kids stop holding hands. Of course, you must have the LED the right way around, and be careful not to short it across the terminals of the power pack. I have a LED that I have soldered a resistor on to to protect it.

Can you see any problems with doing this one Richard?

Regards
Ian

[Loopy]

Ah! Yes the ole VDG...

One of the teachers here remembers quite vividly (with tears in his eyes) of the time he set the VDG up on the bench and had a boy lay hands on it. He was remiss in not noticing the metal cupboard door handle at the right height for the student's genitals... Not a happy chappy...