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Microwave oven

technology Maturity 11-13 Next article →

A microwave oven is an electric appliance used to heat and cook food.

Weibolu
Weibolu

It works by exposing food to electromagnetic radiation. This radiation is in a specific range called the microwave frequency. This process is known as dielectric heating. It allows for very fast and efficient cooking. This is especially true for foods with a high water content.

The mechanism of heating involves a specific interaction with molecules. The oven uses electromagnetic waves to target polar molecules in the food. When these waves hit the molecules, they cause them to rotate rapidly. This rotation produces thermal energy, which we feel as heat.

Magnetron2
Magnetron2

This heating effect is fairly uniform in homogeneous foods. Because the waves penetrate the food, it cooks much faster than conventional methods. However, microwaves rarely cause browning or caramelization. This is because they seldom reach the temperatures needed for Maillard reactions.

Symbol Microwave oven
Symbol Microwave oven

One exception is when the oven heats oily items like bacon. In those cases, the oil can reach much higher temperatures.

There are different ways to manage how heat moves through the food. Some early models used a motor-driven mode stirrer. This device rotates at the top of the oven cavity. This allows the food to remain stationary while the waves move. Other models, like those from Sharp, used a turntable.

Fiskarsin mikrouuni 1965 (2)
Fiskarsin mikrouuni 1965 (2)

The turntable rotates the food itself to promote even heating. Some modern appliances are even more complex. These are called convection microwave ovens. They are hybrid machines that combine microwaves with hot air and infrared radiation. This helps them achieve better results in professional or home cooking.

The history of this technology is tied to military science. In 1940, John Randall and Harry Boot worked in England. They were at the University of Birmingham. They invented the cavity magnetron.

Original cavity magnetron, 1940 (9663811280)
Original cavity magnetron, 1940 (9663811280)

This device could produce electromagnetic waves with very small wavelengths. This was a crucial component for radar during World War II. In 1945, an American engineer named Percy Spencer made a famous discovery. While working at Raytheon, he noticed a candy bar in his pocket had melted. He realized the microwave energy from a radar set caused this. He later tested this by cooking popcorn and an egg.

Burnt popcorn from a microwave
Burnt popcorn from a microwave

Commercial microwave ovens have changed significantly since their debut. Raytheon built the first commercial model, the "Radarange," in 1947.

NS Savannah microwave oven MD8
NS Savannah microwave oven MD8

This early machine was very large and heavy. It consumed 3 kilowatts of power. It even required water-cooling to function. It also cost between $2,000 and $3,000. In 1955, Tappan introduced a built-in model for homes. However, these were still expensive and limited by maintenance needs. The Amana Corporation eventually introduced the first popular countertop model in 1967. This model cost $495 and was much more practical for residential use.

Global adoption of microwave technology has grown rapidly over the decades. In the United States, ownership rose from 1% in 1971 to over 90% by 1997.

1971rr4
1971rr4

In Canada, ownership went from less than 5% in 1979 to over 88% by 1998. Australia saw very high numbers as well. A 2008 study showed 95% of Australian kitchens had a microwave. In France, ownership grew from 40% in 1994 to 65% in 2004. In other places, like India, ownership has been slower. In 2013, only about 5% of Indian households owned one. However, technology is still spreading to many parts of the world.

Today, microwave ovens serve many different purposes. They are common in residential kitchens for reheating food. They are also excellent for items that burn easily, like butter or chocolate.

Control panel on an open microwave oven (125wiki)
Control panel on an open microwave oven (125wiki)

Beyond the home, they are used in many industrial processes.

Microwave tunnel closeup
Microwave tunnel closeup

They provide a way to apply heat to large-scale materials. This shows how a tool originally meant for radar and military use became a standard part of modern life. The transition from a massive, water-cooled machine to a small countertop appliance is a major achievement in engineering.

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🖼️ Images & Media (14)
File:Original cavity magnetron, 1940 (9663811280).jpg
Original cavity magnetron, 1940 (9663811280).jpg
File:Wall of microwaves.JPG
Wall of microwaves.JPG
File:NS Savannah microwave oven MD8.jpg
NS Savannah microwave oven MD8.jpg
File:Fiskarsin mikrouuni 1965 (2).jpg
Fiskarsin mikrouuni 1965 (2).jpg
File:1971rr4.jpg
1971rr4.jpg
File:Symbol Microwave oven.svg
Symbol Microwave oven.svg
File:Weibolu.jpg
Weibolu.jpg
Microwaveoventransient.webm
File:Magnetron2.jpg
Magnetron2.jpg
File:Control panel on an open microwave oven (125wiki).jpg
Control panel on an open microwave oven...
File:Microwave tunnel closeup.jpg
Microwave tunnel closeup.jpg
File:Burnt popcorn from a microwave.jpg
Burnt popcorn from a microwave.jpg

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