How to measure the speed of light with a microwave oven and a regular chocolate bar

Astrophysicist David Berardo of the Massachusetts Institute of Technology invites everyone to conduct a safe experiment at home, which will measure the speed of light using an ordinary chocolate bar and a microwave oven. By the way, after the experiment, chocolate can be eaten without any fear.


First, remove the turntable from the oven and replace it with a plate that can remain stationary during microwave operation. Then place any chocolate bar inside for 20 seconds.

Microwave chocolate

You will see a specific melting pattern that shows the length of the microwaves that your microwave oven’s magnetron generates. If you now measure the length of these waves in centimeters and multiply by the frequency of the furnace radiation, you get a value that is surprisingly close to the speed of light. Almost all microwave ovens have an icon on the back or inside the door that indicates the frequency of the waves they use. Since waves are constantly reflected inside the oven chamber, the numbers are inaccurate – but that doesn’t matter.

Microwave chocolate

The first mention of this experiment appeared on the Internet in 1997, it was based on an older print version from The Physics Teacher magazine, which used marshmallow marshmallow.

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