A microwave oven is a kitchen appliance that is in nearly every U.S. home — 90 percent of households have one, according to the U.S. Bureau of Labor Statistics. With the touch of a couple of buttons, this ubiquitous device can boil water, reheat leftovers, pop popcorn or defrost frozen meats in mere minutes.
The microwave oven was invented at the end of World War II. Yet it took awhile for them to catch on. At first they were too big and expensive, and people didn't trust them because of the radiation they use. Eventually, technology improved and fears faded. By the 2000s, Americans named the microwave oven as the No. 1 technology that made their lives easier, according to J. Carlton Gallawa, author of the Complete Microwave Oven Service Handbook.
And it was all due to a happy accident with some melted chocolate.
Accidental invention
Percy LeBaron Spencer was a self-taught engineer who had never finished grammar school, according to the Southwest Museum of Engineering, Communication and Computation. While at the Raytheon Corp., he worked on magnetrons — vacuum tubes that produce microwave radiation and are used in radar systems. In 1941, he devised a more efficient way to manufacture them. His innovation allowed production to rise from 17 per day to over 2,600 per day.
The first commercial microwave oven was tested in a Boston restaurant in 1947. Later that year, Raytheon introduced the Radarange 1161. It stood 5.5 feet (1.7 meters) tall, weighed 750 lbs. (340 kilograms) and cost $5,000, according to Gallawa. It had to be hooked up to a water line because the magnetron was water-cooled. It took a few years for the public to overcome their initial reluctance but as technology improved, microwave ovens grew in popularity, particularly in the food industry. Restaurants could keep cooked recipes in the refrigerator and heat them to order reducing waste. Other food industry establishments used microwaves for roasting coffee beans and peanuts, defrosting and precooking meat, and even shucking oysters.
How does a microwave work?
Microwave ovens use radio waves set at a specific frequency — 2,450 megahertz with a power ranging from 500 to 1,100 watts, according to the World Health Organization (WHO). Food that sits in a microwave oven is bombarded on all sides by the microwaves. Water molecules within the food absorb the microwaves, and the resulting vibrations generate heat and cook the food. Microwaves pass through plastic, glass and ceramic but not metals, which is why it is not recommended to use metal containers or utensils in a microwave oven, according to SciTech.
A magnetron generates the microwaves. According to EngineerGuy, a magnetron is two permanent magnets on either side of a vacuum tube. Microwave radiation is created by the flow of electrons building up magnetic and electric fields, according to Tech-Faq. The microwaves are directed to the oven chamber in order to heat and cook the food.
