Vitaliy Krasovskiy/Shutterstock

What Happens When You Microwave A Grape?

Microwave at your own risk
Vitaliy Krasovskiy/Shutterstock

If you're bored at home, you could likely use some fun at-home activities to liven things up. If you're trying to entertain kids, there's a wild science experiment you can do that's both destructive and educational. Borrow this popular parlor or science fair trick: Place a grape — almost entirely split down the middle — in a microwave, heat it in the microwave and watch it spark.

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For years, it was unknown exactly why this trick worked. But in 2019, much to the internet’s excitement, a team of physicists found the reason for this phenomenon. Using thermal imagery, computer simulations and videography, the team determined the fire was brought on by microwaves trapped in the grape. 

The grape hemispheres act as spheres of water, which reduce the wavelengths of microwaves. When microwaved as one whole, a grape traps the microwaves in its center. When split in two and placed near each other, the trapped microwaves can hop from grape half to grape half, forming an electromagnetic field that ionizes the grape’s sodium and potassium ions. Then, fire! 

The researchers found no need to leave the grape halves nearly attached. Cutting one down the center or using two whole peeled grapes works just as well. Blueberries and cherry tomatoes do the trick too. 

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