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.
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.
Spencer was testing a magnetron when he noticed that the chocolate bar in his pocket had melted, according to Raytheon’s company history. Intrigued, Spencer tested other foods, including popcorn kernels, and noticed that they all popped. He put an egg near the magnetron and watched as it started to shake and then explode. Spencer realized that the foods had been exposed to low-density microwave energy, according to Gallawa. He next built a metal box and fed microwave power into it. The energy entered the box but could not escape — microwaves do not pass through metal. Spencer discovered that microwaves could cook food faster than convention ovens that used heat. He filed a patent application in 1945. (Spencer went on to receive 150 patents throughout his career, according to the National Inventors Hall of Fame. He died in 1970.)
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.
Other industries also found uses for microwave heating. Microwave ovens are also used to dry cork, ceramics, paper, leather, tobacco, textiles, pencils, flowers, wet books and match heads, according to Gallawa.
Tappan, an appliance maker, introduced the first microwave ovens for home use in 1955, but because of their large size — as big as a stove — and high cost — $1,295 — few were sold, according to Gallawa. Raytheon acquired Amana Refrigeration in 1965, and two years later, the Amana Radarange, which could fit on a kitchen countertop, was introduced. It cost just under $500.
Soon after, microwave ovens became more popular than even the dishwasher due to decreasing sizes and costs. In 1975, only 4 percent of U.S. homes had a microwave oven, according to Gallawa; in 1976, the number jumped to 14 percent. Today, approximately 90 percent of households in the United States have a microwave oven, according to the Bureau of Labor Statistics.
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.
Since their initial development, microwave ovens have gotten a bad rap due to their use of microwave radiation. According to the World Health Organization (WHO), microwave ovens are safe when they are used properly and maintained in good condition. While massive amounts of microwave radiation can be harmful, ovens are designed to keep the radiation within the oven and present only when the oven is switched on and the door is shut. A minimal amount of radiation that may leak, primarily through the glass door, is well below international standards.
According to the WHO, several countries and international standards committees have set a product emission limit of 50 watts per square meter at any point 5 centimeters away from the external surfaces of the oven. In practice, microwave emissions are substantially below this limit. Also, exposure decreases rapidly with distance: a person 50 cm from the oven receives about one one-hundredth of the microwave exposure of a person 5 cm away.
The main health concern when it comes to using microwaves is that in general, microwaves heat unevenly and can cause parts of the food to either be undercooked or extremely hot, so caution is needed — as well as a few extra minutes — for the heat to equalize within the food. The primary injury that results from using a microwave oven is a burn resulting from hot food and liquids or the particles of hot food from explosions from foods, such as eggs in their shells, cooking unevenly.
There are also concerns about the nutritional value of foods after they have been cooked in a microwave oven. According to the WHO, these concerns are based on misconceptions. There is little to no difference in nutritional value of foods cooked in microwave oven versus a conventional oven, nor does cooking food in a microwave oven make the food radioactive.
A 1982 article published in Critical Reviews in Food Science and Nutrition reviewed data from several studies on the effects of microwave cooking on the nutritive values of moisture, protein, carbohydrate, lipid, minerals and vitamins. The authors concluded that no significant nutritional differences exist between foods prepared by conventional and microwave methods.
In 2010, a team of researchers from the Universidad Complutense Madrid in Spain cooked a variety of veggies, from artichokes to zucchini, with techniques ranging from boiling to frying to microwaving. They measured the amount of antioxidants present before and after cooking. They found that baking, griddle-cooking and microwaving produced the lowest losses, while boiling and pressure-cooking were the hardest on antioxidants. Frying was somewhere in between.
The future of microwave ovens
Many microwave ovens today contain sensors that stop themselves when the food has completed cooking, according to SciTech. Samsung (opens in new tab) has developed a microwave oven that offers a variety of cooking methods. In addition to defrosting meats and reheating leftovers, the oven can fry and bake. It also has a fermentation cycle that can be used in making fresh dough and yogurt.
A microwave oven from NXP Semiconductors uses solid-state RF (radiofrequency) energy to cook. The microwave oven controls where, when and the amount of energy that is transmitted directly into the food. The result is improved consistency, taste and nutrition, according to NXP. The solid-state device allows for controlling large amounts of energy with high efficiency and with real-time feedback.
Other companies such as Wayv are producing portable, solid-state RF microwave ovens that can be charged via a regular plug, in the car, or with solar chargers. This particular model, which resembles a thermos, can be used for approximately 30 minutes per charge to heat up to 17 fluid ounces (0.5 liters) at a time.
Microwave ovens are also gaining features to be able to connect to mobile technologies, such as the line of LG smart appliances (opens in new tab). These appliances have the ability to be turned on remotely from anywhere via a smartphone or other device.
- Food and Wine: This New Microwave Could Finally Replace Current 50-Year-Old Technology
- Journal of Microwave Power: The Impact of Microwaves on the Future of the Food Industry: Domestic and Commercial Microwave Ovens
- National Museum of American History: Tappan Model RL-1 Microwave Oven
Live Science Contributor
Rachel Ross is a science writer and editor focusing on astronomy, Earth science, physical science and math. She holds a Bachelor of Arts in Philosophy from the University of California Davis and a Master's degree in astronomy from James Cook University. She also has a certificate in science writing from Stanford University. Prior to becoming a science writer, Rachel worked at the Las Cumbres Observatory in California, where she specialized in education and outreach, supplemented with science research and telescope operations. While studying for her undergraduate degree, Rachel also taught an introduction to astronomy lab and worked with a research astronomer.
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Microwave ovenWho invented the microwave and why? ›
American engineer Percy Spencer is generally credited with inventing the modern microwave oven after World War II from radar technology developed during the war. Named the "Radarange", it was first sold in 1946.Where was the microwave oven invented? ›
The beta microwave was placed in a restaurant in Boston for testing. Raytheon introduced a commercial microwave oven, the 1161 Radarange, in 1954. It was expensive -- priced at $2,000 to $3,000 (the equivalent of $16,000 to $24,000 in today's cash). Raytheon licensed its technology to the Tappan Stove company.Who invented the microwave oven in 1945? ›
Now a staple of the modern kitchen, it was the brainchild of Percy Spencer, a self-educated Maine farm boy with an insatiable curiosity about how the world works. Born in Howland, Maine, in 1894, Spencer was just 18 months old when his father died.Who invented the oven? ›
Ovens in the 1700s
Then a Bavarian architect named François de Cuvilliés invented the first recorded enclosed oven, called the Castrol stove, also known as the stew stove. The enclosed nature of the oven was an innovation as it contained the smoke inside the oven, which had not been done before.
Description. Microwave ovens heat food using microwaves, a form of electromagnetic radiation similar to radio waves. Microwaves have three characteristics that allow them to be used in cooking: they are reflected by metal; they pass through glass, paper, plastic, and similar materials; and they are absorbed by foods.When was the first microwave oven invented? ›
The microwave was invented in 1945 by Raytheon engineer Percy Spencer, as evidenced by his patent for a “Method of treating foodstuffs.”Who invented the microwave Wikipedia? ›
Percy LeBaron Spencer (July 9, 1894 – September 8, 1970) was an American engineer and inventor. He was the inventor the microwave oven. Spencer was born in Maine. He invented the microwave by accident when a chocolate bar his pocket melted when he was performing an experiment.How is a microwave made? ›
How they're made. Microwaves are basically extremely high frequency radio waves, and are made by various types of transmitter. In a mobile phone, they're made by a transmitter chip and an antenna, in a microwave oven they're made by a "magnetron". Their wavelength is usually a couple of centimetres.Who invented the microwave in 1940? ›
The true story is that it was invented utterly by accident one fateful day more than 70 years ago, when a Raytheon engineer named Percy Spencer was testing a military-grade magnetron and suddenly realized his snack had melted.
A Microwave oven is designed to heat most foods in a quick and convenient way. The name Microwave is derived from the energy used to cook the food, microwaves, which pass through the cells and molecules of the food, the frequency of the waves causes the water molecules to vibrate, this movement generates heat.When did ovens get invented? ›
The earliest ovens were found in Central Europe, and date back to 29,000 BC. They were roasting and boiling pits inside yurts used to cook mammoth. In Ukraine from 20,000 BC they used pits with hot coals covered in ashes.What was the first thing microwaved? ›
Microwave cooking oven was patented on October 8, 1945 with the one of the first prototypes placed at a Boston restaurant for testing. The first public was in January 1947 in a Speedy Weeny vending machine in Grand Central Terminal which sold freshly cooked hot dogs.Who first invented stove? ›
The modern kitchen range was invented by Sir Benjamin Thompson, Count Rumford in the 1790s. As an active scientist and prolific inventor, he put the study of heat onto a scientific basis and developed improvements for chimneys, fireplaces and industrial furnaces, which led to his invention of the kitchen range.Is oven and microwave same? ›
Microwave oven, or better known as microwave, uses electromagnetic radiation for heating and cooking. On the other hand, oven is a general term for a thermally insulated chamber which is used for heating, cooking or baking food. Microwave oven heats food efficiently with safe radiation.Who invented to cook? ›
The precise origins of cooking are unknown, but, at some point in the distant past, early humans conquered fire and started using it to prepare food. Researchers have found what appear to be the remains of campfires made 1.5 million years ago by Homo erectus, one of the early human species.How is a microwave used? ›
Cooking with Microwaves
Microwaves are produced inside the oven by an electron tube called a magnetron. The microwaves are reflected within the metal interior of the oven where they are absorbed by food. Microwaves cause water molecules in food to vibrate, producing heat that cooks the food.
The microwave was invented accidentally in 1945 by a self-taught engineer named Percy Spencer, who was leading a radar project for the defence giant, Raytheon. While testing a new vacuum tube called a magnetron, he discovered that a chocolate bar in his pocket had melted from the heat.Can I make pizza in microwave? ›
The answer is yes! Making pizza in microwave ovens is a fairly easy task.Is microwave cooking safe? ›
Food cooked in a microwave oven is as safe, and has the same nutrient value, as food cooked in a conventional oven.
Microwave ovens are generally safe when used correctly. But people have experienced burns, and in rare cases, other injuries from microwave radiation, particularly in cases involving improper use or maintenance.Who discovered microwaves in 1864? ›
James Clerk Maxwell, a brilliant theoretician, predicted the existence of electromagnetic (EM) waves in a paper presented in 1864, although their form was not the four-equation set used today. James Rautio has penned a more complete history of James Clerk Maxwell1 in this issue of Microwave Journal.What are 3 uses of microwaves? ›
Applications of microwaves
The uses of the microwave are similar to that of radio waves. They are used in communications, radio astronomy, remote sensing, radar, and of course, owing to their heating application, they are used in cooking as well.
While lower frequency radio waves can follow the contours of the Earth and bounce off layers in the atmosphere, microwaves only travel line-of-sight, typically limited to 30-40 miles on the Earth's surface.What are the 3 types of oven? ›
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You could say, the kitchen as we know it, began in 1802 with the invention of the range oven. Prior to that, and for hundreds of years, the cooking space was simply a room with a hearth, a wood fire and pots suspended above the heat.What was invented by mistake? ›
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|Known for||Inventor of microwave oven|
|Spouse(s)||Louise Spencer Lillian Ottenheimer Spencer|
One day while working near the magnetrons that produced microwaves, Spencer noticed a peanut butter candy bar in his pocket had begun to melt - shortly after, the microwave oven was born.
Spencer worked for a company named Raytheon, developing microwave radar transmitters during World War II. One day in 1945, he noticed that a candy bar he had in his pocket was starting to melt. The microwaves from the radar set he was working on were cooking the candy bar in his pocket!What did Percy L Spencer invent? ›
Percy Spencer, while working for the Raytheon Company, discovered a more efficient way to manufacture magnetrons. This discovery led to significant advances in radar and his most popular invention, the microwave oven. In 1941, magnetrons were being produced at a rate of 17 per day.What machine did Percy Spencer invent? ›
Percy L. Spencer is best remembered for creating one of the most iconic kitchen appliances, the microwave oven. The inventor was born on July 9, 1894 in Howland, Maine.How much did the guy who invented microwave make? ›
And Maine's own Percy Spencer was paid $2 for inventing the microwave oven. According to the New England Historical Society, Spencer was born in Howland in 1894. His father died 18 months later, and his mother sent him to live with an aunt and uncle.