Read more about invention of microwave oven. There were theories that high-frequency electric fields could be used for heating as early as but this method used frequencies that are lower than those of microwaves. Between and , British physicist Sir John Turton Randall, together with a team of British coworkers, developed multi-cavity magnetron which allowed for production of electromagnetic waves of a small enough wavelength microwaves and development of radar.
Magnetron was given to the U. One of the companies that were given contract by U. In , he was working on powered radar set when he noticed that a chocolate bar that he had in his pocket was melting. He exposed popcorns to microwaves and they popped, he tried the whole egg and it exploded. Then he attached a high density electromagnetic field generator to an enclosed metal box and experimented on food that way which allowed for controlled and safe experimentation.
Microwave cooking oven was patented on October 8, with the one of the first prototypes placed at a Boston restaurant for testing.
The first public was in January in a Speedy Weeny vending machine in Grand Central Terminal which sold freshly cooked hot dogs. The first commercially available microwave oven also appeared in That is almost never the case. Multiple contributors, performing hard work as a team or as individuals, slowly evolve an idea into a product that every once in a while changes the world. Like most other breakthroughs, the microwave oven was a group effort and did not happen overnight.
One of the subject matter experts on this topic is John Osepchuk, who worked at Raytheon during the 60s, 70s and 80s. His papers on the topic include:. MTT, No. John has complained in recent years at IEEE talks that some web sites propose that the microwave oven was invented in Russia, or Germany, but then again, you can find almost any incorrect "fact" you you are looking for on the internet.
Below is a video of John talking about the invention of the microwave oven:. Scott, published in This book commemorates the 50th anniversary of the Raytheon Company. Readers should be aware that such autobiographical efforts contain a wealth of information but have been put through a corporate filter, and can often distort the truth either by omission of details, politics, or simple corporate favoritism.
This web page will draw on Osupchuk's and Scott's publications, as well as the US patent office , and remarkably, the accounts of of an eye witness, a girl who consumed far too many hot dogs as her father tinkered on early oven prototypes in the family garage Much work was afoot in the latter days of W. II by Daddy Warbucks companies looking for industrial heating applications of microwaves, including diathermy, and industrial heating of products such as inks, glue, and tires.
Anyone who worked around the magnetron burn-in stand knew that "soft" objects such as people would start to heat up if they were to stay in the direct path of high-power microwave radiation. Maybe John will send us a picture of the burn-in stand one of these days Spencer's thoughts turned to heating food; legend has it that a candy bar melted in his pocket from stray radiation. However, he could not have been thinking of a consumer application, as the high cost of microwave equipment would prevent widespread home use.
In this patent he points out the choice of frequency which provides high heating efficiency, the size of the cavity, and some superfluous details on the magnetron oscillator itself. He envisioned a conveyor belt for parading the food into the cavity, no mention of safety, or how the radiation might be enclosed or how the food might enter the cavity like a door. In a second patent 2,, Spencer shows the now-ubiquitous use of microwaves to pop popcorn. In a later patent 2,, , filed March 26, , and granted January 30, , entitled "Food Cooking", Spencer discusses how you might "broil" a lobster in a microwave oven, by violating said lobster with a "pencil like rod", in order so that its tail doesn't curl up which would make harder to cook.
And, of course, billions of meals are prepared each day using 2. Radarange was chosen for the product in an employee competition, combining the words radar and range. Why they didn't add a "y" to create "Raydarange" to acknowledge the Raytheon company is a mystery to me Want more pictures like this?
Marshall was president of the company, so it is safe to say his main contribution was leadership; knowing that this was a project worthy of financial support during tough times.
Microwave ovens use radio waves set at a specific frequency — 2, megahertz with a power ranging from to 1, 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 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 , 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.
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