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Q & A: Plasma Ball

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Most recent answer: 10/22/2007
Q:
Please explain about the plasma ball.
- 5B students
Washington School, Monticello, IL USA
A:
As you have probably learned in school, like charges will repel each other and unlike charges will be attracted.

You can think of the plasma ball in the following way: Lots of charges of one kind are put onto the small ball in the center of the sphere, while the outer glass sphere is attached to "ground" (which just means that any charges that get end up on the outer glass sphere have a place to go). Since they are all alike, the charges at the center want to get away from each other. They do this by jumping out to the glass. We can see the jumping electrons (the pretty blue light-streams) since there is a special gas inside the glass sphere that glows wherever the electrons are jumping.

The glowing blue light-streams are called a "plasma", which is why the ball is called a "Plasma Ball". A plasma is actually a fourth state of matter (not a solid a liquid, or a gas) but that's probably a topic for another question.

MS

(published on 10/22/2007)

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