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aluminum foil and TV

K

KellyClarksonTV

Jan 1, 1970
0
Earlier today a rather large piece of aluminum foil jumpped in front of the TV.
When I went to remove it I got a rather painful static shock. I repeated it a
few times, and it seems to occur only right after turning on or turning off the
TV. Anyone able to explain this?
 
R

Rich Webb

Jan 1, 1970
0
Earlier today a rather large piece of aluminum foil jumpped in front of the TV.
When I went to remove it I got a rather painful static shock. I repeated it a
few times, and it seems to occur only right after turning on or turning off the
TV. Anyone able to explain this?

Yes. Apparently, your aluminum foil has been animated by a malign
spirit, a.k.a. "demon" or poltergeist. Seek help immediately!

(Sorry, couldn't resist...)

The TV tube has several electron guns in the rear that paint the glass
face with a negative charge. (Lots of variables involved here, so don't
expect identical results with other TVs, computer monitors, etc.)

When you turn it on, it suddenly charges from ground potential to a
negative potential. Over time, the charge will equalize with the ground
environment and then when you turn it off you end up with a positive
charge on the face.

If you touch the tube with your finger (no foil, yet) you may get a
small spark or, more likely, a barely audible zzt when you release the
static charge on a small portion of the screen. Glass is an insulator,
so your finger only discharges the immediate vicinity.

Slap on the aluminum foil and suddenly you're able to discharge a much
larger surface area, the foil being a somewhat better conductor than
glass.
 
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