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Statically Charged Man Ignites Office
Call Me Black Cloud writes "And you think your coworker with BO is annoying? In this story carried by Reuters, a man wearing a nylon jacket over a wool shirt built up such a static charge that he left a trail of scorched carpet and melted plastic in his wake. After he melted plastic in his car he sought help from firefighters called to the scene, who measured his static field at 40,000 volts." Obviously, despite the fact that this is carried by Reuters, you should take some of the 'facts' presented here with some NaCl.
Its electrifying stories like this that keep me reading slashdot.
-+-=-+-=-+-=-+-=-+-=-+ *** http://www.mountainfort.com *** +-=-+-=-+-=-+-=-+-=-+-
Eletrical Current is measued in Amps, not Volts.
That alone is enough to make me seriously doubt this whole business.
morcego
future Mythbusters in the works...
Any authoritative debunkings yet?
The entire story is laughable, but the most obvious problem is this:
Firefighters took possession of Clewer's jacket and stored it in the courtyard of the fire station, where it continued to give off a strong electrical current.
How does a statically charged jacket "give off an electric current" -- and why would firefighters take possession of it anyway? All they'd need to do to discharge it is pour a bucket of water over it.
Tarsnap: Online backups for the truly paranoid
I have a MSEE and feel like feeding the news trolls.
I put more faith in the Loch Ness Monster than this crap. Shame to see it actually in the "real" news.
1. Current is measured in amps, not volts.
2. WTF is the FIRE department doing with a volt/amp meter? Most (cheap) volt meters don't measure past 1000 volts AC/DC.
3. One or two squirts of water from a spray bottle would have completely discharged the jacket -- assuming somehow the natural humidity didn't!
4. and of course the jacket could never have built up such powerful charges as to melt and burn materials...
5. Seems unlikely that static electricity would be likely to flow *through* plastic, a *non-conductor*.
6. For the jacket to "continue" to give off an electrical current, several things must be happening:
a) There must be somewhere for it to go.
b) There must be something actively ionizing the electronics in the jacket. This requires force, external electricity, etc.
c) The "destination" of the current must also remain oppositely ionized. (Otherwise some current would flow and then things would be balanced). Maintaining the ionization of the "path to the destination" would also require external force, electricity, etc.
You need to calm down. Here, have a cool glass of Dihydrogen Monoxide.
Skype is too convoluted... Now I'm reverse-engineering the Kyoto Protocol.
If it's a hoax, it's fooled a lot of people.
Why would anyone engrave "Elbereth"?
40kV isn't hard to build up. In fact, you can safely play with hundreds of kV, and make some really nice sparks. The 'starting things on fire' number you're looking for is power. And energy. You need to be able to transfer enough energy into an object that it will reach its combustion temperature, and you need to be quick enough at it that the object doesn't shed the energy to nearby objects in the meantime. It takes a lot of energy (as compared to the energy content in your average static 'zap') to set carpet fibers aflame, or even melt them.
Not to say that it didn't happen, of course. It's just not well-reported, and is clearly not terribly common.
High-speed Road Trip (18.000KPH)
I'm thinking that since it appears to be caused by a prolonged rubbing effect ...
more than 70% of Slashdot is in grave danger of undergoing spontaneous human combustion.
A Van De Graaf generator is basically a band of insulating material being rotated in a tower with some means of transferring a charge to it. There are relatively cheap desktop and home models that'll produce nearly half a million volts. Schools use such devices all the time, so if the fireman hasn't seem a voltage that high, he skipped classes.
Having said that, early atom-smashers used Van De Graaf generators only capable of producing five million or so volts. It seems reasonable to suspect something will burn before it is blasted out of existence. So, somewhere between 400,000 volts and 5,000,000 volts, you might be able to ignite something.
However, here we get a problem. You can't just carry around half a million volts and not notice it. Your hair tends to stand on end, for a start. ANYTHING metal - even a doorknob - will cause a discharge to occur. Getting into his car certainly would have - even if the car were carbin-fiber, the key would be metal and the distance short enough for an arc to occur.
There's also the problem of where you lodge a charge that great. A capacitor is basically two electrostatic devices with an insulator between them. In this case, the insulator would be the shoes, and the electrostatic device the person. I'll assume there are enough nails holding the carpet down to act as the other electrostatic device.
But what is the capacitance of a person? The figure I've been able to get with a Google search is an average of 204 pF with a typical range of 95 to 398 pF. (It varies according to height and weight, so a seven-foot sumo wrestler might have a higher capacitance than this range shows.)
In other words, not really what you'd need to carry half a million volts around. The jacket would have carried more, but unless it was made of Tantallum or some other material with very high capacitance, I doubt you'd be able to store enough charge to start setting things on fire.
In other words, there is nothing credible about the story. The voltages are abnormally low for a static device and way too low to actually do any fire damage, there's nowhere a higher charge could have been stored and there would have been too many points at which positively violent arcing would have occurred if it had been stored.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
...wearing a woolen shirt and a synthetic nylon jacket...
As opposed to a natural nylon jacket, made from the finest virgin Icelandic nylon harvested from the nests of shore birds.
I figure by 2030 or so my 6-digit UID will be something to brag about.
Thats what they get for taking the man's stapler. :P