The microwave oven was discovered when a sweet melted in a radar engineer's pocket.
In 1945 Percy Spencer, a self-taught engineer at Raytheon, noticed a candy bar melting in his pocket while he worked on a radar set. He tried popcorn next, then an egg, which exploded in a colleague's face. Two years later his company sold the first microwave oven. It stood nearly two metres tall.
The story starts with radar. In 1940, John Randall and Harry Boot at the University of Birmingham built a working cavity magnetron, a device that could produce powerful short-wavelength microwaves. Britain shared it with the United States that year, and an American historian later called it the most valuable cargo ever brought to American shores. Raytheon was among the firms contracted to mass-produce it.
Percy Spencer, from Howland in Maine, had little formal education but was a skilled engineer at Raytheon. Working near an active radar set in 1945, he noticed microwaves melting a sweet in his pocket. He tested the effect by feeding microwave power into a metal box, from which it could not escape, and watching food heat rapidly. Raytheon filed a patent that October.
The first commercial model, the Radarange, went on sale in 1947. It was almost 1.8 metres tall, weighed about 340 kilograms, used around three times the power of a modern oven and needed water cooling. Early units were leased to hotels and restaurants, and later turned up on trains and ocean liners. Japan's Sharp added the turntable in the mid-1960s, and in 1967 Amana, then owned by Raytheon, launched the first popular countertop model for the home at 495 dollars. Prices fell sharply in the 1980s.
Two myths persist about how it works. Microwaves do not tune into a special resonance of water; they make any polar molecules, such as water and fats, twist back and forth in a rapidly alternating field, generating heat. And they do not cook from the inside out. At the usual 2.45 gigahertz they penetrate only about a centimetre into most foods; the centre is heated by conduction from the outer layer.
Source: Wikipedia — Microwave oven · Text summarised from Wikipedia (CC BY-SA 4.0)
