When you think about plasma,
you know, likewhen you’re just sitting around,
thinking about states of matter,
you probably imaginestars, or the stuff that comes out of a lightsaber.
You probably don’t think about somethingyou’d make in your kitchen microwave.
But it’s totally possible, and there areplenty of YouTube videos to prove it.
Thanks to some cool physics,you don’t even need fancy technology.
All you need is a microwave that you’rewilling to destroy … and a grape.
Plasma is kind of like a gas, except that itsatoms have some of their electrons stripped off,
so it’s made up of positively-chargedions and a bunch of free electrons zooming around.
To make some,you just have to make some gas really hot,
and then send an electrical current through it.
And a microwave is a great way to do that.
Microwave ovens cook food by bathing it ina kind of light called,
They’re just like the visible light comingout of your computer screen right now,
but their frequency, the number of timesthey oscillate back and forth each second,
is about 200,000 times lower, so matter responds differently to them.
The waves make water and other molecules in your food vibrate,
可以生成热量 让你的Hot Pocket变热
which generates the heatthat makes your hot pocket hot.
Now, if you throw a regular old grapein a microwave oven,
it will probably just get really hot and explode.
You’ll get fruit juice all over the insideof the thing, but you won’t see any fireballs.
To get the fiery ball of plasma, the grapeneeds some preparation.
In those YouTube videos, they’re always carefulto cut the grape almost completely in half,
except for a tiny strip of skinconnecting the two halves.
And that strip is important,
because it lets the grape act like an antenna
and that makes the whole experiment work.
A sliced grape happens to be just about theperfect size
to trap and amplify microwaves,
and when the waves start flowing in, the grapeturns into what’s called a dipole antenna,
where the electrical charges in each halfget pushed back and forth across the little slice of skin.
To make sure all the microwaveshit the grape from the same direction,
people will usually take out or coverthe spinning plate that rotates the food,
so the charges bounce back and forthin the same way over and over again.
All that focuses the energy of these microwavesonto that tiny bit of skin.
Any water on there boils away pretty quickly and then,
unsurprisingly, the strip catches on fireafter just a couple of seconds.
Which is one reason whythis is a bad idea to try at home:
Fire and powerful electronics,not usually a good thing to mix together.
But the fire doesn’t just disappear afterthat.
Hot air rises, so the flame climbs up between the two grape halves.
And since the microwave oven is still going,
electric current keeps bouncing back and forth between the sides of the grape,
and across any steam orhot molecules carried up by the fire.
最后当它变的太热的时候 蒸汽 空气 甚至葡萄汁里的原子
Eventually, it gets so hot that the atomsin the steam, the air, and even the grape
juice have their electrons stripped off, andyou get a bunch of plasma.
The plasma fireball shoots out from the grapehalves and, if everything goes just right,
or horribly, horribly wrong, it tends to hitthe roof of the microwave often pretty spectacularly.
Once that fireball stops and it cools down,the plasma just turns into regular gas again,
and there’s nothing to worry about, except,probably, for your broken microwave oven.
Which again, is why this is not a great ideato do in your home microwave oven, which you probably bought with money.
So if you’ve seen these grapesplosions onYouTube,
there’s a lot more to them than meets the eye,
and there’s a lot of coolmicrowave science out there.
But I am not condoning you doing them.
It’s the kind of thing that should be donecarefully by professional grape exploders.
Thanks for watching!
Besides perfectly cut grapes,there are plenty of other things
you should not stick in the microwave, andwe’ve explained some of them before here on SciShow.
If you’ve ever wondered why you shouldn’t put metal in there,
you can watch our episode where we tell you all about it.