Slashdot Mirror
Electromagnetic Emission Art
mr_lithic writes "The artist Richard Box has used the electromagnetic field generated by overhead transmission cables to power 1300 fluorescent lightbulbs positioned underneath. Some pictures available.
Professor Denis Harshaw at Bristol University explains "There's an interactive element to all this, too, for those who go to the site itself. 'You affect the lights by your proximity', explains Richard Box, 'because you're a much better conductor than a glass tube. And there's sound as well as light - a crackling that corresponds to the flashing of the lights. There's a certain smell too, and your hair stands slightly on end.'"
Sounds cool and it is on until February 29th. Directons here."
Its called mutual inductance. The changing magnetic field in the power lines causes a changing magnetic field in the 'pylons'(which are most likely a coil oriented correctly). This causes a current in the coil due to Faraday's law. This current itself then generates its own EMF which Lenz's law then shows will have the opposite polarity of the power line magnetic field. Thus, this new magnetic field attempts to generate a current in the opposite direction in the power lines, increasing their resistance.
In short, he's using the power companies' power to light his bulbs. There are no 'waste emmisions'.
Does arrangements like that actually "steal" any power from the powerlines, or would it be lost anyway if it was just air instead of neon tubes?
They do draw energy from the line. If they weren't there, the voltage differential in the static field would stay high and no (or little) current would be sinked into the ground under the tube.
Another proof: assume each tube spits out the equivalent of 10W in light, there must be like 1000 tubes in that field, so they burn about 10kW all the time. I don't think the ground underneath normally sinks 10kW for each 100mx100m square : if it did, it would heat up, and very long lines would lose so much power over the distance that they would bankrupt the power companies.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
Whatever sucking up EM fields is, it sure isn't theft, no matter what the french say
You shouldn't have slept through your EE classes.
Having a coil under the Eiffel tower is exactly similar to having a secondary coil in a transformer : whenever you have a load drawing current on the secondary coil, the primary coil (in this case, the Eiffel tower's antennas) have to provide that power, despite the fact that there's no physical connection between the 2 coils. So if you have antennas putting out 50kW and a coil drawing 10W nearby, that's 10 less Watts in radio power.
This guy's art also draws energy from the power line. The tubes don't light up for free do they?
But I'll tell you what : if sucking up EM fields isn't theft, tell me where you live and I'll coil a long copper wire around a mile-long stretch of the powerline that goes to your house and power my trailer with it. I'm sure you won't mind the higher bill from the power company in your mailbox, since I'm not stealing anything...
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
Microwaving chocolate is a fun way to both measure the speed of light and get some edible artifacts of the patterns of the electromagnetic fields inside a microwave oven.
Two wrongs don't make a right, but three lefts do.
I'm sure a lot of people here have heard about TDRs being used to troubleshoot network cables.
As for electric companies being called hydro, I'm in Canada (A former British colony and in the Commonwealth) and it's the same here. It really doesn't make that much sense anymore because most power comes from other sources.