How Do Microwaves Work?

Microwave ovens have been with us for so long now, it is hard to remember the days when cooking or reheating weren’t so effortless. Invented in 1946 from radar technology created during World War II, microwave ovens are a fixture in most modern kitchens. According to statistica.com, American consumers purchased almost 12 million microwaves in 2015 and virtually the same amount will likely sell this year.

Microwaves warm our food and beverages in less time and with less energy than a standard oven. Your average home microwave is so simple, but have you ever thought about how they work? Even though the technology is now 70 years-old and may not be as intricate as some newer products, the way these small and incredibly handy ovens operate is still quite ingenious.

The main component in a microwave is the magnetron gun, a high-powered vacuum tube. When activated by electricity, this device gets electrons to vibrate. This releases waves of non-ionized electromagnetic energy. The alternating current in the actual micro waves projects into the unit, through the container or plate you have placed inside, and into the food.

In a regular oven, the outside of the food warms first, with the heat then gradually transferring into the interior. This is an effective way to cook and one that has been with us since our primitive ancestors. However, it does take time. A microwave allows the interior and exterior of the food to heat simultaneously.

The energy directs to the food via a waveguide, which is located in the unit’s wall. Food contains water molecules and these have positive and negative charged ends. The energy in these molecules increases when exposed to the electromagnetic waves. This causes them to change direction back and forth at incredible speed (usually more than two billion times per second). The rocking of the water molecules causes molecular friction, which creates heat. It is this heat that warms or cooks the food.

There is one strange aspect of microwave design. Most people know that you cannot put anything metal in a microwave because it gives off sparks when heated and this can lead to fire. But wait: aren’t the walls of the microwave made of metal? And there is that protective metal mesh (called a Faraday Cage) on the inside window.

The walls of the unit are made of metal because it effectively reflects the waves. This makes the heating process more thorough. The crucial difference is that the walls are thick and flat, so the microwaves bounce off. Objects like a piece of tinfoil or a fork are curved and much thinner, making them far less able to withstand the waves. The holes in the Faraday cage are smaller than a microwave’s wavelength, thus preventing the waves from passing through the glass. You can look through the window all you like—those microwaves are staying inside.

There was controversy years back that the radiation emitted by microwave ovens could cause cancer. Fortunately, this is simply not true. The radiation is quite mild, with a frequency that falls between that put out by infrared lights and the waves that carry programming to your radio. These are far lower than ultraviolet or x-ray waves, which are potentially damaging through excess exposure. Such dangers do not exist from microwave ovens.

Danby microwaves even add extra features like thawing, baking, and reheating settings. Economical, durable, highly reliable, and available in many shapes and sizes, microwaves are the time and energy efficient kitchen appliance for every type of home!