```Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 06:13 PM 3/30/2007, you wrote:
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```Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Jim,

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The movie, I believe, is very revealing. Because of the slow ramp up in voltage before an arc is struck, one can see the affects of the electrostatic attraction before there is any current. As the voltage gets larger, the rods progressively get closer. The scale at the top of the ladder is a great visual aid. There seems to still be a little natural response because the voltage is still changing but is much less in amplitude than when the voltage is applied all at once.
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Once the arc occurs, the electrostatic attraction disappears for the most part and current starts to flow. However, when the arc is at the bottom of the ladder, the current length is very small and the corresponding force should also be small. Notice when the electrostatic attraction disappears. The affect is like a negative unit step frunction and the natural response is excited at its full amplitude. As the arc climbs, the affect of the current becomes greater. I haven't figured out the sign of the magnetic force, but do believe opposite currents will attrract.
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repel.. currents in a loop want to make the loop get bigger..(hence the "work coil" in a quarter shrinker exploding)
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Of course, as Kurt so gently pointed out, I made a huge error in estimating the magnetic forces (what's 6 orders of magnitude among friends, eh?)
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I had a friend that had his plane parked on the tarmac in Florida while on a trip and the tail got struck by lightning. High sheet currents flowed down both sides of the vertical stablelizer and popped the sheet metal off the ribbing. This was clearly a repulsive force when currents flowed in the same direction.
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Gerry R.

Great video Kurt :-))
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