[Steve Kazemir]

Steve Kazemir asked the Naked Scientists:

We recently got a new trampoline for the kids, and we noticed something right away.  When the kids are on it, particularly if they slide around on it, they build up a static charge, and can get zapped, (or zap others).  

My sons were on it at night and could see the sparks….way cool.  

But this got me to thinking, if both of them are sliding around to build up a charge, presumably they would both build up the same charge (positive or negative)?

If so, then whey do they get a spark when they reach towards each other?  Is the spark jumping from the more charged kid to the lesser charged kid?  Would they get a bigger discharge if only one of them slid on the trampoline, and the other stayed neutral?

 Thanks
  Steve


What do you think?

[chris]

I think this is the whole-body equivalent of rubbing a balloon on your hair. The friction between the rubbery material of the trampoline and the body rubs electrons off the body and clothing (and likely carries them to Earth through the frame), leaving the bodies of the bouncers slightly positive.

They can still, nevertheless, shock each other because if one is a bit more positive than the other there is a potential different between them and a current can flow if there is contact.

Chris

[lyner]

I reckon there must be some charging by induction at work here. Most high voltages are produced this way rather than just by 'rubbing'. The Van der Graaph generator relies on it and so does the good old Wimshurst Machine. The energy comes from the jumping up and down.
It's probably very complicated!