Microwave ovens are so quick and efficient because they channel heat energy directly to the molecules (tiny particles) inside food. Microwaves heat food like the sun heats your face—by radiation.
A microwave is much like the electromagnetic waves that zap through the air from TV and radio transmitters. It’s an invisible up-and-down pattern of electricity and magnetism that races through the air at the speed of light (300,000 km or 186,000 miles per second). While radio waves can be very long indeed (some measure tens of kilometers or miles between one wave crest and the next), they can also be tiny: microwaves are effectively the shortest radio
waves—and the microwaves that cook food in your oven are just 12 cm (roughly 5 inches) long.