TI Designs. Find reference designs leveraging the best in TI technology – from embedded processors to analog signal chain and power management. Microwave oven - Wikipedia. A modern microwave oven (2. A microwave oven (commonly referred to as a microwave) is a kitchen appliance that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to rotate and produce thermal energy in a process known as dielectric heating. Microwave ovens heat foods quickly and efficiently because excitation is fairly uniform in the outer 2. 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 1. Raytheon later licensed its patents for a home- use microwave oven that was first introduced by Tappan in 1. The countertop microwave oven was first introduced in 1. Amana Corporation, and their use has spread into commercial and residential kitchens around the world. In addition to their use in cooking food, types of microwave ovens are used for heating in many industrial processes. Microwave ovens are popular for reheating previously cooked foods and cooking a variety of foods. They are also useful for rapid heating of otherwise slowly prepared cooking items, such as hot butter, fats, and chocolate. Unlike conventional ovens, microwave ovens usually do not directly brown or caramelize food, since they rarely attain the necessary temperatures to produce Maillard reactions. Exceptions occur in rare cases where the oven is used to heat frying- oil and other very oily items (such as bacon), which attain far higher temperatures than that of boiling water. Microwave ovens have a limited role in professional cooking,[1] because the boiling- range temperatures produced in especially hydrous foods impede flavors produced by the higher temperatures of frying, browning, or baking.
PDF Book Library Hp Laserjet 9000mfp Service Manuals Summary : File 31,42MB Hp Laserjet 9000mfp Service Manuals Epub Book Scouting for Hp Laserjet 9000mfp Service. However, additional heat sources can be added to microwave ovens, or into combination microwave ovens, to produce these other heating effects, and microwave heating may cut the overall time needed to prepare such dishes. Some modern microwave ovens are part of over- the- range units with built- in extractor hoods. History[edit]Early developments[edit]The exploitation of high- frequency radio waves for heating substances was made possible by the development of vacuum tuberadio transmitters around 1. By 1. 93. 0 the application of short waves to heat human tissue had developed into the medical therapy of diathermy. At the 1. 93. 3 Chicago World's Fair, Westinghouse demonstrated the cooking of foods between two metal plates attached to a 1. W, 6. 0 MHz shortwavetransmitter.[2] The Westinghouse team, led by I. F. Mouromtseff, found that foods like steaks and potatoes could be cooked in minutes. The 1. 93. 7 United States patent application by Bell Laboratories states: [3]"This invention relates to heating systems for dielectric materials and the object of the invention is to heat such materials uniformly and substantially simultaneously throughout their mass. It has been proposed therefore to heat such materials simultaneously throughout their mass by means of the dielectric loss produced in them when they are subjected to a high voltage, high frequency field."However, lower- frequency dielectric heating, as described in the aforementioned patent, is (like induction heating) an electromagnetic heating effect, the result of the so- called near- field effects that exist in an electromagnetic cavity that is small compared with the wavelength of the electromagnetic field. This patent proposed radio frequency heating, at 1. Heating from microwaves that have a wavelength that is small relative to the cavity (as in a modern microwave oven) is due to "far- field" effects that are due to classical electromagnetic radiation that describes freely propagating light and microwaves suitably far from their source. Nevertheless, the primary heating effect of all types of electromagnetic fields at both radio and microwave frequencies occurs via the dielectric heating effect, as polarized molecules are affected by a rapidly alternating electric field. Cavity magnetron[edit]. Microwave ovens, several from the 1. The invention of the cavity magnetron made possible the production of electromagnetic waves of a small enough wavelength (microwaves). The magnetron was originally a crucial component in the development of short wavelength radar during World War II.[5] In 1. British physicist Sir John Turton Randall, FRSE, together with a team of British coworkers, for the British and American military radar installations in World War II. A more high- powered microwave generator that worked at shorter wavelengths was needed, and in 1. University of Birmingham in England, Randall and Harry Boot produced a working prototype.[6]Sir Henry Tizard travelled to the U. S. in late September 1. Tizard Mission). An early 6 k. W version, built in England by the General Electric Company Research Laboratories, Wembley, London, was given to the U. S. government in September 1. The magnetron was later described by American historian James Phinney Baxter III as "[t]he most valuable cargo ever brought to our shores".[7] Contracts were awarded to Raytheon and other companies for mass production of the magnetron. Discovery[edit]In 1. Percy Spencer, an American self- taught engineer from Howland, Maine. Employed by Raytheon at the time, he noticed that microwaves from an active radar set he was working on started to melt a candy bar he had in his pocket. The first food deliberately cooked with Spencer's microwave was popcorn, and the second was an egg, which exploded in the face of one of the experimenters.[8][9] To verify his finding, Spencer created a high density electromagnetic field by feeding microwave power from a magnetron into a metal box from which it had no way to escape. When food was placed in the box with the microwave energy, the temperature of the food rose rapidly. On 8 October 1. 94. Raytheon filed a United States patent application for Spencer's microwave cooking process, and an oven that heated food using microwave energy from a magnetron was soon placed in a Boston restaurant for testing. Commercial availability[edit]. Raytheon Rada. Range aboard the NS Savannah nuclear- powered cargo ship, installed circa 1. In 1. 94. 7, Raytheon built the "Radarange", the first commercially available microwave oven.[1. It was almost 1. 8 metres (5 ft 1. US$5,0. 00 ($5. 4,0. It consumed 3 kilowatts, about three times as much as today's microwave ovens, and was water- cooled. An early Radarange was installed (and remains) in the galley of the nuclear- powered passenger/cargo ship NS Savannah. An early commercial model introduced in 1. US$2,0. 00 to US$3,0. Raytheon licensed its technology to the Tappan Stove company of Mansfield, Ohio in 1. They tried to market a large 2. US$1,2. 95 ($1. 2,0. In 1. 96. 5, Raytheon acquired Amana. In 1. 96. 7, they introduced the first popular home model, the countertop Radarange, at a price of US$4. In the 1. 96. 0s,[specify]Litton bought Studebaker's Franklin Manufacturing assets, which had been manufacturing magnetrons and building and selling microwave ovens similar to the Radarange. Litton then developed a new configuration of the microwave: the short, wide shape that is now common. The magnetron feed was also unique. This resulted in an oven that could survive a no- load condition: an empty microwave oven where there is nothing to absorb the microwaves. The new oven was shown at a trade show in Chicago,[citation needed] and helped begin a rapid growth of the market for home microwave ovens. Sales volume of 4. U. S. industry in 1. Market penetration was faster in Japan, due to a re- engineered magnetron allowing for less expensive units. Several other companies joined in the market, and for a time most systems were built by defense contractors, who were most familiar with the magnetron. Litton was particularly well known in the restaurant business. Radar Range RR- 4. By the late 1. 97. Often called "electronic ovens" in the 1. Formerly found only in large industrial applications, microwave ovens increasingly became a standard fixture of residential kitchens in developed countries. By 1. 98. 6, roughly 2. U. S. owned a microwave oven, up from only about 1% in 1. U. S. Bureau of Labor Statistics reported that over 9. American households owned a microwave oven in 1. In Australia, a 2. In Canada, fewer than 5% of households had a microwave oven in 1. In France, 4. 0% of households owned a microwave oven in 1.
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