Why does a grape in a microwave create plasma?

[MournSanity]

I'm sure many of you have seen this phenomena. I did it the other day. I took a grape and cut it straight down the middle but left a little skin on the bottom. I put it in the "hot spot" of my microwave for 10 seconds and it started sparking and then a ball of plasma rose up out of the grape. It was the sweetest thing ever. You can google it if you have no clue what I'm talking about.

Why does this happen? I'm looking for the scientific reason behind this, as I'm sure there is one. It boggles my mind because a microwave has nowhere NEAR enough power to superheat air into plasma.

Here's a video of what I'm talking about.

 

[PottedMeat]

my guess is that the two halves act as a dipole antenna at microwave frequencies. the "antenna" picks up enough energy and high currents are induced in the grape. the point of highest resistance is the little part in the middle so thats where it heats up the most, eventually burning through.

 

[lexxmac]

Here's a good answer to your question (found on, where else, google):

http://www.madsci.org/posts/archives/dec97/882909591.Ph.r.html

 

[RadBrad]

Originally posted by: lexxmac
Here's a good answer to your question (found on, where else, google):

http://www.madsci.org/posts/archives/dec97/882909591.Ph.r.html

That was a very effecient, highly technical method of killing this otherwise fascinating post. I now understand why my grape would not ignite.

 

[DrPizza]

I haven't tried it, but heard that it works better if you use HALF of a grape, and split that in half again, leaving the skin attached as you described. For more fun, convince coworkers that you saw on 20/20 or so other such documentary show that they discovered that they use mercury and cadmium to fertilize the grapes in foreign countries, because the metal gets into the grape and makes it taste sweeter and last longer. A quick demonstration with this experiment, and you'll usually hook any disbelievers in the crowd.

 

[stardust]

Originally posted by: DrPizza
I haven't tried it, but heard that it works better if you use HALF of a grape, and split that in half again, leaving the skin attached as you described. For more fun, convince coworkers that you saw on 20/20 or so other such documentary show that they discovered that they use mercury and cadmium to fertilize the grapes in foreign countries, because the metal gets into the grape and makes it taste sweeter and last longer. A quick demonstration with this experiment, and you'll usually hook any disbelievers in the crowd.

umm, which crowd would that be? why not just say your backyard is radioactive and spare the "geekiness"
then again, it wouldn't be highly technical.

my physics professor demonstrated this experiment in class a few months back. you should also try soap in the microwave.

 

[DrPizza]

Oh, of course I've tried soap in the microwave. And LED's, and florescent light bulbs, and lit candles, and the entire bottom lined with marshmellows (to measure the wavelength/frequency of the microwave), regular light bulbs, and coasters (CDR's and DVDR's).

Hint, experiment with such things only if you don't mind possibly needing to buy a new microwave.

 

[OpTiX]

Originally posted by: DrPizza
Oh, of course I've tried soap in the microwave. And LED's, and florescent light bulbs, and lit candles, and the entire bottom lined with marshmellows (to measure the wavelength/frequency of the microwave), regular light bulbs, and coasters (CDR's and DVDR's).

Hint, experiment with such things only if you don't mind possibly needing to buy a new microwave.

im gonna try all that......................one day

 

[tranceport]

cool. me too. I'm gonna buy some grapes tonight.

 

[capybara]

um, id love to see the video, but i get this error: file type = video clip (not mpeg)
windows media player error. unable to decompress. i know i can play mpegs, but whats this? video clip isnt a file type is it?

 

[pbi]

quicktime movie

 

[Sunner]

Originally posted by: capybara
um, id love to see the video, but i get this error: file type = video clip (not mpeg)
windows media player error. unable to decompress. i know i can play mpegs, but whats this? video clip isnt a file type is it?

Try VLC.
That way you won't have to install SlowTime.

 

[Eraserface]

Does this work with grape wine or juice?