CAUTION!! 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!


We’re going to create the fourth state of matter in your microwave using food.  Note – this is NOT the kind of plasma doctors talk about that’s associated with blood.  These are two entirely different things that just happen to have the same name.  It’s like the word ‘trunk’, which could be either the storage compartment of a car or an elephant’s nose.  Make sense?


Plasma is what happens when you add enough energy (often in the form of raising the 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.  Anytime you have charged particles (like naked electrons) off on their own, they are referred to by scientists as ions.  Hopefully this makes the dry textbook definition make more sense now (“Plasma is an ionized gas.”)


So here’s what you need:


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  • microwave (not a new or expensive one)
  • a grape
  • a knife with adult help


 
Download Student Worksheet & Exercises


1. Carefully cut the grape almost in half. You want to leave a bit of skin connecting the two halves.


2. Open the grape like a book. In other words, so that the two halves are next to one another still attached by the skin.


3. Put the grape into the microwave with the outside part of the grape facing down and the inside part facing up.


4. Close the door and set the microwave for ten seconds. You may want to dim the lights in the room.


s2You should see a bluish or yellowish light coming from the middle section of the grape. 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.


Note: This experiment creates a momentary, high-amp short-circuit in the oven, a lot like shorting your stereo with low-resistance speakers. It’s not good to operate a microwave for long periods with little to nothing in them.  This is why we only do it for a few seconds. While this normally isn’t a problem in most microwaves, don’t do this experiment with an expensive microwave or one that’s had consistent problems, as this might push it over the edge.


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Comments

215 Responses to “Plasma Grape”

  1. SOOO COOL
    What makes this happen?

  2. Aurora Lipper says:

    An explanation provided in 2019 by the Proceedings of the National Academy of Sciences states that when two pieces of grape are close to each other in a microwave, the waves they absorb bounce back and forth in the tiny space between them, creating an increasingly powerful electromagnetic field. This continues until the electromagnetic field becomes so powerful that it supercharges nearby electrolytes that then shoot out in a brief explosion of fiery plasma.

  3. hopeinhisluv says:

    What exactly is happening?

  4. No there is no risk of fire, as long as you follow the directions and have the help of an adult.

  5. wendysbutler says:

    can this set fire to a microwave

  6. This is safe if you follow all directions and have the help of an adult.

  7. carolinametzgers says:

    It looks and sounds dangerous. Is this safe?

  8. I’ve never tried an apple, and if you read over the comments you’ll find other items that people have tried and worked. I am guessing that the apple is too big to form the ionized gaseous cloud within the membrane (not enough water), but I will have to think about what’s going on to be sure.

  9. Delia Ayer says:

    Why did you use a grape. Why not an apple. What’s the chemical reaction?

  11. Melissa Heath says:

    is the grape supposed to smoke?

    -Thomas

  12. Sparked is just fine – you’re looking for an indication of energy, and sometimes it just sparks and other times it flares up, depending on the power of your microwave and how juicy that grape is.

  13. Shaun Herring says:

    Ours sparkled instead of the arc shown in the video? Did we do something wrong?

  14. Well, you are basically short circuiting your microwave, and if you aren’t fast enough to stop it in time, it might damage the interior with an arc. So I would try an old one.

  15. Twila Dawe says:

    The reason for using an old microwave is that this experiment may damage it?