|MLA Citation:||Bloomfield, Louis A. "Question 540"|
How Everything Works 21 Jan 2018. 21 Jan 2018 <http://howeverythingworks.org/print1.php?QNum=540>.
If you were to freeze an electromagnetic wave at one instant and look at its structure in space, you would find that its electric and magnetic fields had a periodic spatial structure. Just as a water wave has crests and troughs, an electromagnetic wave has spatial fluctuations in its two fields. The distance between adjacent "crests" in either one of these fields is that wave's wavelength. Different types of electromagnetic waves have different wavelengths. Radio waves have long wavelengths that range from about 1 meter to hundreds or even thousands of meters and visible light has short wavelengths that range from about 400 billionths of a meter (400 nanometers) to about 750 billionths of a meter (750 nanometers). Microwaves are those electromagnetic waves with wavelengths between 1 millimeter and 1 meter. The microwaves used in microwave cooking have wavelengths of 12.2 centimeters.
Microwaves are often used to carry information in satellite communication and telephone microwave links. Whenever you see a dish antenna (a satellite dish or a communication link dish on a building or tower), you are looking at a microwave system. Astronomers use radio telescopes to look at microwave emissions from celestial objects. Radar bounces microwaves from objects to determine where they are or how fast they're moving. And microwave ovens use microwaves to add thermal energy to water molecules in order to heat food.