Dancing Ice?

This one was rejected as a “Question of the Week”, and it was suggested that I post it here. After some thought, I decided, “What the heck!”

Interesting things happen when you’re hung over…

Specifically:

For lunch today, I decided to have a "microwaveable" frozen dinner

(Specifically, a “Linda McCartney Southwestern Style Rice and Beans”). When
I removed it from the box, I noticed something flitting around inside the
container, looking not unlike a tiny moth or white insect. I watched in
morbid fascination as it danced to and fro, jumping from the plastic film,
down to the food, and hovering in between. It actually moved horizontally
also, about 1.5". I removed my glasses to get a closer look and saw that it
was a small (about 3/16") chunk of frost merrily dancing around in there.
Needless to say, I was astounded (and pleased that it wasn’t a bad case
of the DT’s) and intrigued by this display, and when the frost finally
settled back down, I attempted to re-create the effect by re-inserting the
tray into the cardboard container and removing it quickly, but with no
result.
I’m sure that the phenomenon was caused by static electricity, but I’ve
never seen this particular effect before, and I eat a lot of frozen dinners.

*Of course, the fact that Linda McCartney (may she rest in peace) is

deceased did not escape my twisted sense of humor.*

The amount of frost inside the package was a bit excessive, indicating

extended storage time or elevation of temperature and re-freezing at some
point.

Question: Have you (or any of your esteemed colleagues) ever seen this

before? What caused the rapid “dancing” behavior? Am I just nuts?

My best guess for this is that the little fleck of ice was carrying a small current from the plastic film to the food inside.

There’s an experiment that I can’t find an online description of that’s rather like this. You take an electric circult and create a break in it. On the ends of the wires at the break mount two metal plates facing each other. Position them a few inches apart and hang a ping-pong ball covered with conductive paint between them. If you start the ball swinging it will bounce back and forth between the two plates, powered by the electricity.

As it touches one plate the paint charges up to that polarity. This causes the ball to be repelled and attracted to the other plate where the same thing happens all over again. The bouncing ball manages to transfer a small flow of current around the circult in this manner.

It sounds like the piece of ice was playing the part of the ball carrying charge between the film and food which were acting like the metal plates at different potentials.

weird. i wonder why it kept going for so long - I mean, that top plastic sheet shouldn’t hold THAT much charge should it?

How long did you nuke this thing? Seems like frost would melt - dissolve or something. Actually even anything alive wouldn’t survive after a 1 minute microwave blast. (I think) (I hope!)

Jake, I think that this was before he nuked it. He took it out of the box, but it was still inthe tray and plastic wrapping.

It sounds like static.
Doed this fit the description…

1)Something peeled or pulled of the plastic film covering, taking electrons with it, forming an electric potential between the film and the food.

  1. Since the meal was frozen, the humidity is low between film and food and thus a leak of charge via water vapour between the two was impaired.

  2. A small peice of light frost acted as a means of balancing the charge, first attracted to the film, then dropping its charge and falling back to the food. This cycled a few times until the charge was balanced between film and food.

To reproduce the effect, try recharging the plastic film by rubbing it with a polyester cloth. The food must be very cold first to hold the charge.

Thanks, all.
I was just curious if anyone else had witnessed such a display… it was just the damndest thing I’d ever seen. Static electricity generally behaves, well, statically. “antechinus” seems to be closest to what I was thinking. It must have been the uneven distribution of water vapor that caused the erratic “dancing” behavior of the particle. Then, the charge on the plastic film drained off.
damndest thing…

Happy Holidays
Shaker

Two demonstrations from physics class:

“Volta’s Hailstorm”

Put some rice crispies or carbon-coated styrofoam beads on a metal plate. Place a shallow plastic box upside-down over them. Rub the top of the box with wool, fur, saran wrap etc. The particles will wildly “dance” as they’re attracted from one surface to the other (and discharging that surface when they touch it.)

“Franklin’s Pendulum” (Armilla describes it.)

Sounds like the plastic covering of your food became charged up and started causing the “Volta’s Hailstorm” dance.

And as for “static electricity” being “static”, see:

Electrostatic motor: http://amasci.com/emotor/emotor.html

What is “static” electricity? http://amasci.com/elect/elefaq1.html#g1

“Static Electricity” is not static (unmoving): http://www.amasci.com/emotor/stmiscon.html#one

Thanks, bbeaty! The name “Volta’s Hailstorm” is certainly an apt description being that ice was involved. Now I can tell my co-workers the story, and when they give me that funny look, I’ll reply: “…It was merely a variant of the “Volta’s Hailstorm” phenonemon!”

Hah!

cheers,

shaker