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September 15, 2007 11:54 PM   Subscribe

Why did my casserole just shock me?

Just got up for some leftovers, and got 2 static shocks from my potato/onion/cheese/bacon casserole.

Details (more if needed): Got up from my computer chair here in Mississippi, where it has been the nicest night in forever--much drier and cooler than it has been. Went to the refrigerator in my linoleum-floored kitchen from a wood floor, bare-footed. Got the (plastic with screw-on plastic top) container of casserole and sniffed it. Got big-time shocked on my nose, then, a few moments later while I was complaining to my SO about it, got shocked on my finger while pointing at the food. I actually saw a spark with the second shock.

I understand static shocks in general, and get them often in the winter. But a shock from what amounts to a potato salad in a plastic container? What gives?
posted by thebrokedown to Grab Bag (7 answers total) 1 user marked this as a favorite
Dry + cool = more static. Here in Fairbanks, AK (where "cool" and "dry" is a massive understatement in the winter months), most of the time from October to April it feels like everything is static. Touching anything plastic, metal, or natural fabric is asking for a shock. We start grounding ourselves on a metal post before touching the electronics when the electrical season, err, winter starts.
posted by Cricket at 12:08 AM on September 16, 2007

Does plastic do that? Didn't know. But, this was definitely the foodstuff itself.
posted by thebrokedown at 12:10 AM on September 16, 2007

The somewhat-conductive food inside an insulating plastic container might be acting a little like a Leyden jar capacitor.

Interesting experience. I wonder if it could be turned into some sort of screwy science demonstration.
posted by hattifattener at 12:39 AM on September 16, 2007 [1 favorite]

Did you charge yourself up via the plastic wheels on your computer chair when you got up? They can sometimes be quite effective little generators, and maybe your feet were dry enough to not discharge through the wood/lino.
posted by malevolent at 1:58 AM on September 16, 2007

...and got 2 static shocks from my potato/onion/cheese/bacon casserole.

I think I'm gonna needd that recipe for some, uh, independent research.
posted by grateful at 8:50 AM on September 16, 2007

I used sour cream rather than mayo.

(Sorry no link; I continue to have an odd problem with cutting and pasting into the link field on MeFi using Firefox.)
posted by thebrokedown at 10:02 AM on September 16, 2007

I really like hattifattener's answer, and I think it deserves further exploration.

First, where was the initial charge or charge separation? Was it on you or the potato salad and container? You were sitting in front of a computer for awhile; if it has a CRT display, you were sitting in an electric field which could have charged you to a considerable voltage. Despite that potato batteries are almost as much a staple of elementary science demonstration tables as they were on tables of the poor in pre-1850 Ireland, I can't think of a mechanism whereby your potato salad could generate and sustain the voltage (aka potential difference) necessary to jump a gap the way it did when you pointed at it.

Second, if your potato salad did accept the charge on you the way a Leyden Jar would have, how do we account for such remarkably elevated capacitance in such an humble dish? I'd tentatively put it down to the gel (sol, if you prefer) character of the sour cream, where very small droplets are dispersed in another medium, in this case droplets of (dielectric) fat in a salt-water (conductive) matrix, I believe, leading to the very large surface area for the charge to sit on, in a small volume, which is the source of the amazing capacitance of aero-gels as well, for example.

If this is right, as far as patents are concerned, I certainly haven't heard of any liquid-in-liquid sol capacitors, say a teflon ether (for its tremendous dielectric constant) in water, previously.
posted by jamjam at 12:12 PM on September 16, 2007

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