Infinite Powers: How Calculus Reveals the Secrets of the Universe

by Steven H. Strogatz

For a standard microwave oven that runs at 2.45 GHz (meaning the waves vibrate back and forth 2.45 billion times a second), you should find that the distance between neighboring melted spots is about two and a half inches, or six centimeters. Keep in mind, that’s only the distance from a peak to a trough and hence is half a wavelength. To get the full wavelength, we double that distance. Thus the wavelength of the standing-wave pattern in the oven is about five inches, or twelve centimeters. Incidentally, you can use your oven to calculate the speed of light. Multiply the frequency of vibration (listed on the oven’s door frame) by the wavelength you measured in your experiment, and you should get the speed of light or something pretty close to it. Here’s how it would go with the numbers I just gave: The frequency is 2.45 billion cycles per second. The wavelength is 12 centimeters (per cycle). Multiplying them together gives 29.4 billion centimeters per second. That’s pretty close to the accepted value for the speed of light, 30 billion centimeters per second.