How Microwaves Work

microwaves

Microwave ovens make thawing, cooking and reheating foods a snap. They can reduce the amount of time you spend at the stove and eliminate the need for other appliances such as toaster ovens or grills. They also help food cook faster and save energy by requiring less power than conventional ovens.

The key to microwaves is their ability to penetrate water, fat and sugar molecules without being absorbed. Unlike radio waves, which require a direct line of sight to reach their destination, microwaves can travel through the Earth’s atmosphere. But as the frequency increases, the atmosphere becomes increasingly opaque. At 100 GHz, atmospheric gases begin to absorb microwaves completely.

Water molecules are particularly sensitive to microwaves, says Louis Bloomfield, a physics professor at the University of Virginia. He explains that a single water molecule has two smaller positively charged hydrogen atoms and one larger negatively charged oxygen atom. When microwaves pass through the body of a water molecule they cause these atoms to twist and vibrate 2.5 billion times per second. These vibrations create friction, which generates heat.

The resulting electromagnetic field, or microwaves, are used for point-to-point communication links and broadcasting. They’re especially suitable for wireless networks because they can be focused into narrow beams with greater precision than radio waves, allowing for more efficient use of the available spectrum. Microwaves are also used for radar, such as that found on aircraft and ships, and weather forecasting. They’re often used in collision avoidance systems, garage door openers and household electronics such as mobile phones.