Frostbite Theater

Polar Molecules

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(How Does a Van de Graaff Generator Work?)

How Does a Van de Graaff Generator Work?

Static Electricity and Bubbles!

What happens when soap bubbles are blown into the air near a working Van de Graaff generator?

Announcer: Frostbite Theater presents... Cold Cuts! No baloney!

Joanna and Steve: Just science!

Joanna: Hi! I'm Joanna!

Steve: And I'm Steve!

Joanna: And this is a Van de Graaff generator!

Steve: And these... are bubbles!

Joanna: Have you ever noticed that you tend to get shocked less in the summer by static electricity than you do in the winter? That's because usually there's more moisture in the air in the summer than in the winter. Since water molecules are polar, they are attracted to, and carry charge away from, charged objects.

Steve: Now, we can't the water molecules in the air, but we can use the bubbles to figure out what they're doing. When the Van de Graaff is off and uncharged, the bubbles behave just as you would expect them to.

Joanna: When the dome is charged, things change. The bubbles are attracted to the dome. Some of the bubbles pick up charge in the air on their way to the dome. If they pick up enough charge before they run into the dome, they'll be repelled by it. The bubbles fly away, carrying charge with them.

Steve: There's less moisture in the air in winter, so that's like having only a few bubbles in the air at one time. The dome holds its charge longer because they're fewer things taking the charge away from it.

Joanna: In the summer, there's more moisture in the air, so that's like having a lot of bubbles.

Steve: Oh!

Joanna: Allow me!

The more moisture that's in the air, the faster the dome loses its charge.

Thanks for watching! I hope you'll join us again soon for another experiment!

Steve: Bubble fight!

Joanna: I think I'm losing!

Steve: Superior firepower does not ensure victory!

Joanna: They're coming back at me!

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