On October 25, 1955, Tappan Stove Company sold the first domestic microwave oven, a large, 220V wall unit priced at $1295.

The expensive ovens did not sell well and Tappan eventually put microwave ovens on the back burner, as it was. Tappan had licensed its microwave technology from Raytheon, which had in 1947 built the “Radarange.”

The Radarange, the first microwave oven, stood nearly 6 feet tall and weighed about 750 pounds. The tubes in the magnetron that generated the microwaves had to be water-cooled, so it required plumbing.

In the 1960s, defense company Litton Industries bought Studebaker's Franklin Manufacturing assets, which had been selling microwave ovens similar to the Radarange. Litton re-engineered the devices, allowing for a shorter, wider shape that more easily fit on kitchen countertops. In 1967, Raytheon introduced the first popular home model, the countertop Radarange, priced at $495, through its recently acquired company Amana Corp.

Defense companies were the leading manufacturers of microwave ovens through the 1970s. Such companies were most familiar with microwave technology, which was first used for radar in the 1940s. In fact, the idea to use microwaves to cook food was born shortly after World War II.

American self-taught engineer Percy Spencer was working at Raytheon at the time. He was working on an active microwave radar set, just after high-powered microwave radar transmitters were developed and widely disseminated by the Allies of World War II, using the British magnetron technology that was shared with Raytheon. While running tests on the equipment, he noticed that the Mr Goodbar candy bar he had in his pocket started to melt. The radar had melted his chocolate bar with microwaves.

To verify his finding, Spencer created a high density electromagnetic field by feeding microwave power from a magnetron into a secured metal box. When food was placed in the box, its temperature rose rapidly.

The first food to be deliberately cooked with Spencer's microwave was popcorn. The second food to be cooked was an egg, which exploded in the face of one of the experimenters.

Now more often referred to simply as microwaves, the ovens are no longer primarily manufactured by defense companies. It has been estimated that more than 90% of American homes have a microwave.

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Editor's note : This article was originally posted on October 25, 2012 and edited on October 25, 2019.