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Encyclopedia > Microwave oven
Microwave oven
Microwave oven

A microwave oven, or microwave, is a kitchen appliance employing microwave radiation primarily to cook or heat food. Microwave ovens have revolutionized food preparation since their use became widespread in the 1970s. Image File history File links Derived from public domain images featured at: http://commons. ... It has been suggested that this article be split into articles entitled Microwave oven and Microwave heating. ... A combined microwave and fan-assisted oven. ... A combined microwave and fan-assisted oven. ... A kitchen is a room used for food preparation and sometimes entertainment. ... Home appliances are electrical/mechanical appliances which accomplish some household functions, such as cooking or cleaning. ... This article is about the type of Electromagnetic radiation. ... Cooking is the act of preparing food. ...

Contents

History

Cooking food with microwaves was discovered by Percy Spencer while building magnetrons for radar sets at Raytheon. He was working on an active radar set when he noticed a strange sensation, and saw that a peanut chocolate bar he had in his pocket started to melt. Although he was not the first to notice this phenomenon, as the holder of 120 patents, Spencer was no stranger to discovery and experiment, and realized what was happening. The radar had melted his candy bar with microwaves. The first food to be deliberately cooked with microwaves was popcorn, and the second was an egg, which exploded in the face of one of the experimenters. [citation needed] Percy Lebaron Spencer (July 9, 1894 - September 8, 1970), an American, was the inventor of the microwave oven. ... A cavity magnetron is a high-powered vacuum tube that generates coherent microwaves. ... For other uses, see Radar (disambiguation). ... Raytheon Company (NYSE: RTN) is a major American defense contractor and industrial corporation with core manufacturing concentrations in defense systems and defense and commercial electronics. ... Binomial name L. This article is about the legume. ... For other uses, see Patent (disambiguation). ... For other uses, see Popcorn (disambiguation). ...


On October 8, 1945 Raytheon filed a patent for Spencer's microwave cooking process and in 1947, the company built the first microwave oven, the Radarange. It was almost 6 feet (1.8 m) tall and weighed 750 pounds (340 kg). It was water-cooled and consumed 3000 watts, about three times as much as today's microwave ovens. An early commercial model introduced in 1954 generated 1600 watts and sold for $2,000 to $3,000. Raytheon licensed its technology to the Tappan Stove company in 1952. They tried to market a large, 220 volt, wall unit as a home microwave oven in 1955 for a price of $1,295, but it did not sell well. In 1965 Raytheon acquired Amana, which introduced the first popular home model, the countertop Radarange in 1967 at a price of $495. is the 281st day of the year (282nd in leap years) in the Gregorian calendar. ... Year 1945 (MCMXLV) was a common year starting on Monday (link will display the full calendar). ... For other uses, see Watt (disambiguation). ... Tappan is a brand of stoves owned by Electrolux. ... The Amana Corporation was founded by George Foerstner as Amana Refrigeration in 1934 in Amana, Iowa to manufacture commercial walk-in coolers. ...


In the 1960s, 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 indefinitely. The new oven was shown at a trade show in Chicago, and helped begin a rapid growth of the market for home microwave ovens. Sales volume of 40,000 units for the US industry in 1970 grew to one million by 1975. Market penetration in Japan, which had learned to build less expensive units by re-engineering a cheaper magnetron, was faster. Litton Industries was a large defense contractor in the United States, bought by the Northrop Grumman Corporation in 2001. ... Studebaker Corporation, or simply Studebaker, was a United States wagon and automobile manufacturer based in South Bend, Indiana. ... A trade fair (or trade show) is an exhibition organised so that companies in a specific industry can showcase and demonstrate their new products and services. ... Nickname: Motto: Urbs in Horto (Latin: City in a Garden), I Will Location in the Chicago metro area and Illinois Coordinates: , Country State Counties Cook, DuPage Settled 1770s Incorporated March 4, 1837 Government  - Mayor Richard M. Daley (D) Area  - City 234. ...


Several other companies joined in the market, and for a time most systems were built by defense contractors, who were the most familiar with the magnetron. Litton was particularly well known in the restaurant business. By the late 1970s the technology had improved to the point where prices were falling rapidly. Formerly found only in large industrial applications, microwave ovens (often referred to informally as simply "microwaves") were increasingly becoming a standard fixture of most kitchens. The rapidly falling price of microprocessors also helped by adding electronic controls to make the ovens easier to use. By the late 1980s they were almost universal in the US and had taken off in many other parts of the globe. Current estimates hold that nearly 95% of American households have a microwave [citation needed]. A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ...


Currently, the Chinese firm Galanz is the largest maker of microwave ovens in the world[citation needed]. Annually the firm produces over 15 million appliances accounting for 40% of the global market. Galanz (Galanz Enterprise Group Co. ...


Principles

Magnetron with section removed (magnet is not shown)
Magnetron with section removed (magnet is not shown)

A microwave oven consists of: Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ...

A microwave oven works by passing nonionizing microwave radiation, usually at a frequency of 2.45 GHz (a wavelength of 12.24 cm), through the food. Microwave radiation is between common radio and infrared frequencies. Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating. Many molecules (such as those of water) are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. This molecular movement creates heat as the rotating molecules hit other molecules and put them into motion. Microwave heating is most efficient on liquid water, and much less so on fats and sugars (which have less molecular dipole moment), and frozen water (where the molecules are not free to rotate). Microwave heating is sometimes explained as a rotational resonance of water molecules, but this is incorrect: such resonance only occurs in water vapour at much higher frequencies, at about 20 gigahertz. For other uses, see Transformer (disambiguation). ... A cavity magnetron is a high-powered vacuum tube that generates coherent microwaves. ... It has been suggested that this article or section be merged with embedded microprocessor. ... It has been suggested that this article or section be merged with Waveguide (optics). ... Non-ionizing radiation (or, esp. ... Microwave Slang for small waves, like at a beach, often used by surfers. ... For other uses, see Frequency (disambiguation). ... A gigahertz is a billion hertz or a thousand megahertz, a measure of frequency. ... For other uses, see Wavelength (disambiguation). ... This article is about the unit of length. ... H2O and HOH redirect here. ... For other uses, see FAT. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... Dielectric heating is the phenomenon in which radiowave or microwave electromagnetic radiation heats a dielectric material, especially as caused by Dipole rotation. There are two principal mechanisms by which a non-conductive material can be warmed in an EM field: Electrical conduction: current flow in the oscillating electric field allows... The Earths magnetic field, which is approximately a dipole. ... For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ... Dipole moment refers to the quality of a system to behave like a dipole. ... This article is about resonance in physics. ... Look up giga- in Wiktionary, the free dictionary. ... This article is about the SI unit of frequency. ...


A common misconception is that microwave ovens cook food from the "inside out". In reality, microwaves are absorbed in the outer layers of food in a manner somewhat similar to heat from other methods. The misconception arises because microwaves penetrate dry nonconductive substances at the surfaces of many common foods, and thus often deposit initial heat more deeply than other methods. Depending on water content, the depth of initial heat deposition may be several centimeters or more with microwave ovens, in contrast to broiling (infrared) or convection heating, which deposit heat thinly at the food surface. Depth of penetration of microwaves is dependent on food composition and the frequency, with lower microwave frequencies penetrating better. Wikibooks Cookbook has more about this subject: Broiling Broiling is a process of cooking food with high heat with the heat applied directly to the food, most commonly from above. ...


Most microwave ovens allow the user to choose between several power levels, including one or more defrosting levels. In most ovens, however, there is no change in the intensity of the microwave radiation; instead, the magnetron is turned on and off in cycles of several seconds at a time. This can actually be observed when microwaving airy foods which may inflate during heating phases, and deflate when the magnetron is turned off. Newer models have inverter power supplies which provide truly continuous low-power microwave heating.


The cooking chamber itself is a Faraday cage enclosure which prevents the microwaves from escaping into the environment. The oven door is usually a glass panel for easy viewing, but has a layer of conductive mesh to maintain the shielding. Because the size of the perforations in the mesh is much less than the wavelength of 12 cm, most of the microwave radiation cannot pass through the door, while visible light (with a much shorter wavelength) can. With wireless computer networks gaining in popularity, microwave interference has become a concern near wireless networks. Microwave ovens are capable of disrupting wireless network transmissions because the ovens generate radio waves of about 2.45 GHz in the 802.11b/g frequency band, some of them escaping the enclosure despite the presence of the mesh. Entrance to a Faraday room A Faraday cage or Faraday shield is an enclosure formed by conducting material, or by a mesh of such material. ... For other uses, see Wavelength (disambiguation). ... For other uses, see Light (disambiguation). ... Wireless networks are telephone or computer networks that use radio as their carrier or physical layer. ... Wi-Fi (or Wi-fi, WiFi, Wifi, wifi), short for Wireless Fidelity, is a set of standards for wireless local area networks (WLAN) currently based on the IEEE 802. ...


Microwave ovens are generally used for time efficiency in both industrial applications such as restaurants and at home, rather than for cooking quality, although some modern recipes using microwave ovens rival recipes using traditional ovens and stoves. Professional chefs generally find microwave ovens to be of limited usefulness because the Maillard reactions cannot occur due to the temperature range.[1]. On the other hand, people who want fast cooking times can use microwave ovens to prepare food or to reheat stored food (including commercially available pre-cooked frozen dishes) in only a few minutes. Popcorn is one example of a very popular item with microwave oven users. For other uses, see Chef (disambiguation). ... The Maillard reaction is a chemical reaction between an amino acid and a reducing sugar, usually requiring the addition of heat. ... For other uses, see Popcorn (disambiguation). ...


A variant of the conventional microwave is the convection microwave. A convection microwave is a combination of a standard microwave and a convection oven. It allows food to be cooked quickly, yet come out browned or crisped, as from a convection oven. Convection microwaves are more expensive than a conventional microwave. They are not considered cost-effective if primarily used just to heat drinks or frozen food. They are usually used for cooking a prepared dish. A Convection Microwave is a combination of a standard microwave oven, and a Convection oven. ... Convection ovens use heated air that is forced into the oven by fans located in the back of the oven, generally for cooking food. ...


More recently, certain manufacturers have added a high power quartz halogen bulb to their convection microwave models while marketing them under names such as "Speedcook", "Advantium" and "Optimawave" to emphasize their ability to cook food rapidly and with the same browning results typically expected of a conventional oven. This is achieved using the high intensity halogen lights at the top of the microwave to deposit large amounts of infrared radiation to the surface of the food. The food browns while also being heated internally by the microwave radiation and heated through conduction and convection by contact with heated air - produced by the conventional convection portion of the unit. The IR energy which is rapidly delivered to the outer surface of food by the lamps is sufficient to initiate browning and caramelization reactions in a particular food's proteins and carbohydrates, producing a texture and taste much more similar to that typically expected of conventional oven cooking rather than the bland boiled and steamed taste that microwave-only cooking tends to create. For other uses, see Quartz (disambiguation). ... An incandescent light bulb and its glowing filament. ... Advantium is the brand name of an electric food oven produced by General Electric since 1999. ... For other uses, see Infrared (disambiguation). ... This article does not cite any references or sources. ... Carbohydrates (literally hydrates of carbon) are chemical compounds that act as the primary biological means of storing or consuming energy, other forms being fat and protein. ...


In order to aid browning, sometimes an accessory browning tray is used. This article is considered orphaned, since there are very few or no other articles that link to this one. ...


Sizes

Consumer microwaves typically come in two types in three sizes.

  • Compact Microwave- A compact microwave, also called small or portable, is the smallest type of typically available consumer microwave. Compacts are the most popular size of microwave oven. A typical model is no more than 18 inches wide (46 cm) and 14 inches (35.5 cm) or less deep and 12 inches (30.5 cm) or less tall. These ovens are rated between 500 and 1000 watts of power and measure less than 1 cubic foot (28 L) in capacity. These ovens are primarily used for reheating food and making microwave meals and popcorn. The largest models will accommodate a 2 quart round casserole dish and are suitable for light cooking. These ovens are not made to cook large amounts of food. Their compact size and low wattage make these ovens ubiquitous in college dormitories and office breakrooms everywhere. Typically these models cost less than $100 US.
  • Medium Capacity Microwave-These microwaves are larger than compact microwaves. Their heights and depths are only marginally larger than compacts, but they are typically 20 inches (50 cm) wide or more. Their interiors are typically between 1 and 1.5 cubic feet (28 to 43 L) and power runs from 1000-1500 watts. These are the standard "family" sized microwave. They cook marginally faster and can accommodate small square casseroles, large round casseroles, and large bowls. They are suitable for cooking vegetables and small pieces of meat and large frozen entrees. They have a few more "auto-cook" features.
  • Large Capacity- These are big microwaves designed for cooking meals. Large capacity ovens can handle 9x13 inch (23x33 cm) casserole dishes, cook tall items like roasts or turkey breast, and have a large number of "auto-cook" and precise temperature control measures. Large capacity oven normally use over 2000 watts and have over two cubic feet (56 L) of capacity. These ovens are normally well-over 20 inches (50 cm) wide, as much as 20 inches deep, and 12 inches (30 cm) or more high.
  • Counter Top microwaves dominate the market. These ovens are designed to sit on a counter or table.
  • Built In microwaves are ovens that are built into the cabinetry similar to traditional ovens. These ovens are typically more expensive than countertops. Some built in microwaves are combined with an exhaust fan for installation above a cooktop.

Increasingly, microwaves are sold with additional features including combining them with convection cooking, "top browning" elements that will brown food (similar to the broiling function on an oven) and even rotisseries in the oven. Most microwaves have white enamel interiors but high end models are often stainless steel, like the original Radarange. A stove is a heat-producing device. ...


Efficiency

A microwave oven only converts part of its electrical input into microwave energy. A typical consumer microwave oven consumes 1100 W of electricity in producing 700 W of microwave power, an efficiency of 64%. The other 400 W are dissipated as heat, mostly in the magnetron tube. Additional power is used to operate the lamps, AC power transformer, magnetron cooling fan, food turntable motor and the control circuits. This waste heat, along with heat from the food, is exhausted as warm air through cooling vents.


Safety and controversy

The dominant view has been that microwaved food is safe to eat. Microwave ovens have become a fairly standard item in most western homes. Microwaving food is fast, energy efficient, and arguably is healthier than traditional means of cooking. Even those who take this view still concede a number of potential safety issues.


Safety benefits

Commercial microwave ovens all use a timer in their standard operating mode; when the timer runs out, the oven turns itself off.


Microwave ovens heat food without getting hot themselves. Taking a pot off a stove, with the exception of an induction cooktop, leaves a potentially dangerous heating element or trivet that will stay hot for some time. Likewise, when taking a casserole out of a conventional oven, one's arms are exposed to the very hot walls of the oven. A microwave oven does not pose this problem. An induction cooker uses induction heating for cooking. ...


Food and cookware taken out of a microwave oven is rarely much hotter than 100 °C (212 °F). Cookware used in a microwave oven is often much cooler than the food because the microwaves heat the food directly and the cookware is heated by the food. Food and cookware from a conventional oven, on the other hand, are the same temperature as the rest of the oven; a typical cooking temperature is 180 °C (360 °F). That means that conventional stoves and ovens can cause more serious burns.


The lower temperature of cooking (the boiling point of water) is a significant safety benefit compared to baking in the oven or frying, because it eliminates the formation of tars and char, which are carcinogenic. Microwave radiation also penetrates deeper than direct heat, so that the food is heated by its own internal water content. In contrast, direct heat can fry the surface while the inside is still cold. Pre-heating the food in a microwave oven before putting it into the grill or pan reduces the time needed to heat up the food and reduces the formation of carcinogenic char. In pathology, a carcinogen is any substance or agent that promotes cancer. ...


Uneven heating, deliberate and otherwise

In a microwave oven, food may be heated for so short a time that it is cooked unevenly, since heat requires time to diffuse through food, and microwaves only penetrate to a limited depth. Microwave ovens are frequently used for reheating previously cooked food, and bacterial contamination may not be killed if the safe temperature is not reached, resulting in foodborne illness. This article is about food. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Food safety is a scientific discipline describing the handling, preparation, and storage of food in ways that prevent Foodborne illness. ... A foodborne illness (also foodborne disease) is any illness resulting from the consumption of food. ...


Uneven heating in microwaved food is partly due to the uneven distribution of microwave energy inside the oven, and partly due to the different rates of energy absorption in different parts of the food. The first problem is reduced by a stirrer, a type of fan that reflects microwave energy to different parts of the oven as it rotates, or by a turntable or carousel that turns the food; turntables, however, may still leave spots, such as the center of the oven, which receive uneven energy distribution. The reflection of a bridge in Indianapolis, Indianas Central Canal. ...


The second problem is due to food composition and geometry, and must be addressed by the cook by arranging the food so that it absorbs energy evenly, and periodically testing and shielding any parts of the food that overheat. In some materials with low thermal conductivity, where dielectric constant increases with temperature, microwave heating can cause localized thermal runaway. As an example, uneven heating in frozen foods is a particular problem, since ice absorbs microwave energy to a lesser extent than liquid water, leading to defrosted sections of food warming faster due to more rapid heat deposition there. Due to this phenomenon, microwave ovens set at too-high power levels may even start to cook the edges of the frozen food, while the inside of the food remains frozen. Another case of uneven heating can be observed in baked goods containing berries. In these items, the berries absorb more energy than the drier surrounding bread and also cannot dissipate the heat due to the low thermal conductivity of the bread. The result is frequently the overheating of the berries relative to the rest of the food. The low power levels which mark the "defrost" oven setting are designed to allow time for heat to be conducted from areas which absorb heat more readily to those which heat more slowly. RF shielding is the protection of sensitive electrical equipment from external radiofrequency (RF) electromagnetic radiation by enclosing it in a conducting material. ... K value redirects here. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... This article is about Thermal runaway. ...


Microwave heating can be deliberately uneven by design. Some microwavable packages (notably pies) may contain ceramic or aluminum-flake containing materials which are designed to absorb microwaves and heat up which aids in baking or crust preparation. Such ceramic patches affixed to cardboard are positioned next to the food, and are typically smokey blue or gray in color, usually making them easily identifiable. Microwavable cardboard packaging may also contain overhead ceramic patches which function in the same way. The technical term for such a microwave-absorbing patch is a susceptor. A susceptor is a material used for its ability to absorb electromagnetic energy. ...


Dangers

A microwaved DVD-R showing the effects of electrical discharge through its metal film
A microwaved DVD-R showing the effects of electrical discharge through its metal film
See also: Microwave-related injury

Liquids, when heated in a microwave oven in a container with a smooth surface, can superheat; that is, reach temperatures that are a few degrees in temperature above their normal boiling point, without actually boiling. The boiling process can start explosively when the liquid is disturbed, such as when the operator takes hold of the container to remove it from the oven or while adding impurities such as powdered creamer or sugar, and can then result in a violent burst of water and vapor resulting in liquid and steam burns. A common myth states that only distilled water can exhibit this behavior; this is not true.[2] ImageMetadata File history File links Download high resolution version (2560x1920, 3678 KB) A maxell DVD-R that was microwaved. ... ImageMetadata File history File links Download high resolution version (2560x1920, 3678 KB) A maxell DVD-R that was microwaved. ... A DVD+R disc The title given to this article is incorrect due to technical limitations. ... Microwave ovens can be the cause of injuries and deaths In recent times, there have been microwave-related injuries and a few microwave-related deaths. ... In physics, superheating (sometimes referred to as boiling retardation, boiling delay, or defervescence) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. ... A steam explosion (also called a littoral explosion, or fuel-coolant interaction, FCI) is a violent boiling or flashing of water into steam, occurring when water is either superheated, or rapidly heated by fine hot debris produced within it. ... Bottle for Distilled water in the Real Farmacia in Madrid. ...


Closed containers and eggs can explode when heated in a microwave oven due to the pressure build-up of steam. Products that are heated too long can catch fire. Though this is inherent to any form of cooking, the rapid cooking and unattended nature of microwave oven use results in additional hazard. Microwave oven manuals frequently warn of such hazards, but many of them are difficult to foresee. Because the microwave oven's cavity is enclosed and metal, fires are generally well contained. Simply switching off the oven and allowing the fire to consume available oxygen with the door closed will typically contain damage to the oven itself. An egg is a body consisting of an ovum surrounded by layers of membranes and an outer casing of some type, which acts to nourish and protect a developing embryo. ... For other uses, see Steam (disambiguation). ...


Any metal or conductive object placed into the microwave will act as an antenna to some degree, resulting in an electric current. This causes the object to act as a heating element. This effect varies with the object's shape and composition. A Yagi-Uda beam antenna Short Wave Curtain Antenna (Moosbrunn, Austria) A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia) An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. ... City lights viewed in a motion blurred exposure. ... In electronics, and in physics more broadly, Joule heating or ohmic heating refers to the increase in temperature of a conductor as a result of resistance to an electrical current flowing through it. ...


Any object containing pointed metal can create an electric arc (cause sparks) when microwaved. This includes cutlery, aluminium foil, ceramics decorated with metal, and most anything containing any type of metal. Forks are a good example. This is because the tines of the fork resonate with the microwave radiation and produce high voltage at the tips. This has the effect of exceeding the dielectric breakdown of air, about 3 megavolts per meter (3×106 V/m). The air forms a conductive plasma, which is visible as a spark. The plasma and the tines may then form a conductive loop, which may be a more effective antenna, resulting in a longer lived spark. Any time dielectric breakdown occurs in air, some ozone and nitrogen oxides are formed, both of which are toxic. Microwaving food containing an individual smooth metal object without pointed ends (for example, a spoon) usually does not produce sparking. A 3000 volt electricity arc between two nails Electricity arcs between the power rail and electrical pickup shoe on a London Underground train An electric arc can melt calcium oxide An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current... Used cutlery: a plate, a fork and knife, and a drinking glass. ... This article does not cite any references or sources. ... Look up tine in Wiktionary, the free dictionary. ... Microwave Slang for small waves, like at a beach, often used by surfers. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... The term electrical breakdown has several similar but distinctly different meanings. ... Josephson junction array chip developed by NIST as a standard volt. ... The metre, or meter (symbol: m) is the SI base unit of length. ... For other uses, see Plasma. ... For other uses, see Ozone (disambiguation). ... The term nitrogen oxide is a general term and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2) Dinitrogen monoxide (N2O) (Nitrous oxide) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen...


The effect can be seen clearly on a CD or DVD. The electric current heats the metal film, melting the plastic in the disc and leaving a visible pattern of concentric and radial scars. It can also be illustrated by placing a radiometer inside the cooking chamber, creating plasma inside the vacuum chamber. CD may stand for: Compact Disc Canadian Forces Decoration Cash Dispenser (at least used in Japan) CD LPMud Driver Centrum-Demokraterne (Centre Democrats of Denmark) Certificate of Deposit České Dráhy (Czech Railways) Chad (NATO country code) Chalmers Datorförening (computer club of the Chalmers University of Technology) a 1960s... DVD (also known as Digital Versatile Disc or Digital Video Disc) is a popular optical disc storage media format. ... A radiometer is a device used to measure the radiant flux or power in electromagnetic radiation. ...

A microwave oven with a metal shelf
A microwave oven with a metal shelf

Several microwave fires have been noted where Chinese takeout boxes with a metal handle are microwaved. Twist ties containing metal wire and paper are also notoriously dangerous. Image File history File links Download high resolution version (1800x1200, 404 KB)A microwave oven with its metal shelf. ... Image File history File links Download high resolution version (1800x1200, 404 KB)A microwave oven with its metal shelf. ... American Chinese cuisine refers to the style of food served by Chinese restaurants in the United States. ... Wikipedia does not yet have an article with this exact name. ...


Another hazard is the resonance of the magnetron tube itself. If the microwave is run without an object to absorb the radiation, a standing wave will form. The energy is reflected back and forth between the tube and the cooking chamber. This may cause the tube to cook itself and burn out. Thus dehydrated food, or food wrapped in metal which does not arc, is problematic without being an obvious fire hazard. Vibration and standing waves in a string, The fundamental and the first 6 overtones A standing wave, also known as a stationary wave, is a wave that remains in a constant position. ... Drying is a method of food preservation that works by removing water from the food, which prevents the growth of microorganisms and decay. ...


Certain foods if carefully arranged can also produce arcing, such as grapes.[3] A naked flame, being made of conductive plasma, will do the same.

Further information: St. Elmo's fire

St. ...

Controversial hazards

Radiation

Some people are concerned with being exposed to the microwave radiation. According to the United States Food and Drug Administration's Center for Devices and Radiological Health, a U.S. Federal standard limits microwave leakage from an oven, for the lifetime of the device, to 5 milliwatts per square centimeter when measured 2 inches from the surface of the oven.[4] This is far below the exposure level that is currently considered to be harmful to human health.


The radiation produced by a microwave oven is non-ionizing. As such, it does not have the specific cancer risks associated with ionizing radiation such as X-rays, ultraviolet light, and high-energy particles. Any health problems would result from electric currents induced in the body, most prominently cataract formation. Long-term rodent studies to assess cancer risk have so far failed to clearly identify any carcinogenicity from 2.45 GHz microwave radiation at chronic (large fraction of life span) exposure levels, far larger than humans are likely to encounter even from leaking ovens.[5][6] Non-ionising radiation (or in American English non-ionizing radiation) refers to any type of electromagnetic radiation that does not carry enough energy to ionize living material - that is, to completely remove an electron from an atom or molecule. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... Radiation hazard symbol. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... Human eye cross-sectional view, showing position of human lens. ...


To put the radiation hazard into perspective, the formation of carcinogenic char in conventional frying pan or oven needs to be taken into account (see above). The carcinogens in char are toxicated into carcinogens that are radiomimetic (i.e. cause damage similar to ionizing radiation). Microwaving instead of frying or cooking in the oven eliminates this danger. In pathology, a carcinogen is any substance or agent that promotes cancer. ... Look up char in Wiktionary, the free dictionary. ... Toxication is the process of drug metabolism in which the metabolite of a compound is more toxic than the parent drug or chemical. ... Radiation hazard symbol. ...

Effects on food and nutrients

There have been studies on the effects of microwave cooking. They show both positive and negative effects on the nutrient contents of food which has been microwaved.

  • 1992, Pediatrics, Volume: 89, Issue 4,pp. 667-669, Effects of microwave radiation on anti-infective factors in human milk by R Quan, C Yang, S Rubinstein, NJ Lewiston, P Sunshine, DK Stevenson and JA Kerner
  • 1994, Journal of Nutrition and Food Science, Volume: 95 Issue: 4 Page: 8 - 10, Nutritional effects of microwave cooking by Anne Lassen, Lars Ovesen
  • 1998, Journal of Agricultural and Food Chemistry, Effects of microwave heating on the loss of vitamin B12 in foods by Fumio Watanabe,* Katsuo Abe, Tomoyuki Fujita, Mashahiro Goto, Miki Hiemori, and Yoshihisa Nakano
  • 2003, Journal of the Science of Food and Agriculture, Volume 83, Issue 14 , Pages 1511 - 1516, Phenolic compound contents in edible parts of broccoli inflorescences after domestic cooking by F Vallejo, FA Tomás-Barberán, C García-Viguera.

See also

A TV Dinner (also called frozen dinner, microwave meal or ready meal) is a prepackaged, frozen or chilled meal which usually comes in an individual package. ... Microwave chemistry is the science of applying microwave irradiation to chemical reactions . Microwaves act as high frequency electric fields and will generally heat anything with a mobile electric charge. ... Induction Hob (Top View) An induction cooker uses induction heating for cooking. ...

Notes

  1. ^ Hervé This, Révélations gastronomiques, Éditions Belin. ISBN 2-7011-1756-9
  2. ^ Unwise Microwave Oven Experiments
  3. ^ "Why do grapes spark in the microwave?" MadSci Network
  4. ^ US Food and Drug Administration on safety of microwave ovens
  5. ^ PMID 9806599
  6. ^ PMID 9453703

References

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  Results from FactBites:
 
Microwave Oven (499 words)
But remember that the microwave oven can not do it all, a meal made solely in a microwave oven is no meal but a snack and should not be considered as anything else.
The microwave oven did not become cheap and easy enough to be bought by the ordinary man until the late 80s and that is when the microwave oven boom spread across the globe, resulting in that the microwave oven today is a standard household appliance everywhere.
The microwave oven uses the fact that water molecules among many other molecules are electric dipoles, meaning that they are not perfectly balanced when it comes to electrical charge having one negative side and one positive one.
Microwave Oven (3564 words)
The microwave oven was invented as an accidental by-product of war-time (World War 2) radar research using magnetrons (vacuum tubes that produce microwave radiation, a type of electromagnetic radiation that has a wavelength between 1 mm and 30 cm).
An oven that heated food using microwave energy was then placed in a Boston restaurant for testing.
Microwave ovens were a spin-off of wartime RADAR, and invented accidentally by Percy LeBaron Spencer of Raytheon while working on a magnetron (radar tube) near the end of the war.
  More results at FactBites »

 
 

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