How to measure the speed of light with a liquorice stick

Try the following experiment at home (all you need is a liquorice stick and a microwave oven):

Can you guess why the value you have calculated is the speed of light?
First of all, let's explain how the microwave oven works.

The oven acts as a cavity for the waves; thus, the waves are no longer travelling waves, but standing waves.

As you can see in the video, the amplitude remains zero at some points which are separated half wavelenght. For this reason, the stick is not burnt at these points.

Since the speed of light is the product of the frequency (given by the oven specifications) by the wavelength, which can be deduced from the distance between two non-burnt points, it is easy to get a good approximation for it.

This experiment has been adapted from "Cuaderno de bitácora estalar"