(just one of the GREAT articles in our Science Anyone? edition)
How many kinds of matter are there? Most of us were taught that there are three: Solid, Liquid and Gas.
Actually, there are two more. The fourth kind or “state” of matter is called “plasma” (Note – this is NOT the kind of plasma doctors talk about that’s associated with blood. Same word, totally different meaning). Plasma is the stuff that engines for spaceships in sci-fi movies like Star Trek supposedly use.
Today, you’re going to learn how to safely make plasma in your microwave! It’s WAY cool.
Here’s all you need:
- A microwave oven
- A grape
- A knife, with adult help
- A plate
(Pretty easy so far, right?)
To make the experiment easier, I’ve actually made a short video that shows you step-by-step how to do it. Go to this link to watch the video:
If you’re not near a computer, here are the general steps. It’s just a lot easier to see exactly how to cut the grape, and what the plasma looks like when you can watch it on video, so do check it out when you can.
Here are the steps…
Be careful with this!! This experiment uses a knife AND a microwave, so you’re playing with things that slice and gets things hot. If you’re not careful you could cut yourself or burn yourself. Please use care!
- Carefully cut the grape almost in half. You want to leave a bit of skin connecting the two halves, but not too much or it won’t work well.
- Open the grape like a book. In other words, so that the two halves are next to one another still attached by the skin.
- Put the grape into the microwave with the outside part of the grape facing down and the inside part facing up.
- Close the door and set the microwave for ten seconds. You may want to dim the lights in the room.
You should see a bluish or yellowish light coming from the middle section of the grape. If you get it right, you can get the rising plasma ball effect like the video shows.
This is plasma!
Be careful not to overcook the grape. It will smoke and stink if you let it overcook. Also, make sure the grape has time to cool before taking it out of the microwave.
Other places you can find plasma include neon signs, fluorescent lights, plasma globes, and small traces of it are found in a flame.
What’s Going On?
Plasma is what happens when you add enough energy (often in the form of rising temperature) to a gas so that the electrons break free and start zinging around on their own.
Since electrons have a negative charge, having a bunch of free-riding electrons causes the gas to become electrically charged.
This gives some cool properties to the gas, like the ability to conduct electricity and also to glow (give off light).
Anytime you have charged particles (like naked electrons) off on their own, they are referred to by scientists as ions.
The microwave cooks your dinner by shooting “light” beams at the food. These light beams are specially tuned to a frequency that increases the energy of the water molecules inside your food.
Grapes are made mostly with juice that conducts electricity (think of how salt water conducts electricity). The grape halves are like little cups full of this conductive juice connected by a tiny bridge (the part that you didn’t cut all the way through).
When you hit the START button on the microwave, the energy being shot at your grape moves the electrolytes across the bridge very quickly, which heats up the bridge until it bursts into flame.
The electrons that are traveling through the flame zip across and mix with the air, and a burst of bright plasma shoots up. If you watch carefully, you will see two flames, not one.
If you want to learn more about plasma and the states of matter, as well as ideas for more plasma experiments, you can access these for free at:
About Aurora Lipper
Aurora is a real rocket scientist. She worked for NASA, has designed rockets, has 3 patents for her inventions, holds a graduate degree in mechanical engineering, did PhD work at Stanford University, has taught on the faculty of Cal Poly University (she was the youngest faculty member ever hired by the Mechanical Engineering dept.), has taught K-12 science to well over 10,000 kids, is a licensed pilot, and currently serves as president of the California Central Coast Astronomical Society. AND, she is a stay-at-home mom to 4 kids.