How to Make Plasma Balls in a Microwave Oven?

Answer 1

One simple science experiment that you can try with your kids to teach them about the four phases of matter is using a microwave oven and a couple of grapes to create balls of plasma. Matter is the stuff that all things in the universe are made from. There are four phases of matter: solid, liquid, gas, and plasma. Almost all kids are familiar with solids, liquids, and gases, but under normal circumstances, there is not a lot of plasma to be seen on earth at close range. Using your microwave oven, though, you can induce plasma to form, allowing your kids to see the fourth phase of matter.

To perform this experiment, you will need some seedless grapes, a knife for cutting, a small plate, paper towels, and a microwave oven. Please note that although this experiment is relatively safe, plasma does present a fire risk, which may damage your microwave oven or cause bodily injury. Proceed with caution and adult supervision.

First, slice the seedless grapes in half, leaving the two halves attached by a thin piece of skin. Place several on a microwave oven proof plate and dry them off without crushing the grapes or separating the halves. Please be careful and only microwave one or two grapes at a time.

Next, microwave the grape(s) on high for 30 seconds. Magically, the grapes will start to spark and burst into blue to purple flames. The flames that you see are plasma, the fourth state of matter.

What has caused the grapes to burst into balls of plasma? Grapes are full of juice, which contains substances called electrolytes that can conduct electricity. When the microwave turns on and exposes the grape halves to energy, the thin membrane that attaches each grape half to one another forms a conductive path through which current can flow from one half of the grape to the next. This current flows from side to side through the thin, skin bridge which causes it to heat up to over 3000 degrees. When the temperature gets this extreme, the skin bursts into flames. Energy is still flowing throughout the microwave during this time, which causes the air in the flame and around the grape to ionize and turn into plasma that is blue or purple.