IT’S FAST. REALLY FAST. But you know that already: it’s 186,000 miles a second. But don’t take my word for it; you can work it out for yourself. All you need is a microwave oven and a plate of grated cheese.
Spread the cheese evenly on the plate, and take the turntable out of the microwave. Put the plate in and cook it for around 20 seconds, until the cheese starts to melt.
When you take it out you’ll see hot spots of melted cheese. Measure the distance between them with a ruler, in centimetres. They’ll most likely be between six and 12 centimetres apart. This corresponds to half the wavelength of the microwave.
Now look on the back of your microwave, and you’ll see the frequency of your model listed. It’s usually around 2450 Mhz. All you have to do is to double the measured distance (so you get a full wavelength, rather than just half) and multiply it by 1000*, then multiply it by the frequency of the microwave, and you’ll get the number of metres per second. It should come to about 299,800,000. If it doesn’t, you need to replace your microwave. Or your cheese.
*The frequency is measured in Mhz, which is a million Hertz. To be pedantic you should first divide your measurement by 1000 to get the distance in metres and then multiply it by a million, but I didn’t want to put you through the extra step.
