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Name: John A.
Status: other
Age: 50s
Location: N/A
Country: N/A
Date: Sunday, September 15, 2002


Question:
Years ago I saw an experiment using a Van De Graaff generator wherein a pointed rod repelled static electricity and when a rounded tip was installed over the point, the static jumped to the rod. The purpose of the experiment was to show the importance of having the rod pointed on the end, and seemed to imply that it kept lightning from striking, rather than carry the charge to ground, which seems to be the conventional wisdom.

Have you ever observed this experiment? What were the results?


Replies:
Yes, I know the experiment. It illustrates that the electric field is larger wherever a conductor has a smaller radius and is greatest at sharp points. The high electric field can cause electrons to be pushed off (or strongly attracted to) the pointed rod. Pointed rods do indeed tend to keep lightning from striking, but it is precisely because the large electric fields generate large currents, which then reduce the charge in the clouds and so prevent lightning. If you could remove all the excess charges from the clouds, there would be no lighting at all.

Best, Dick Plano



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