How much did the first microwave oven cost?

In 1947, Raytheon built the "Radarange", the first commercially available microwave oven. It was almost tall, weighed and cost about US$5,000 ($ in dollars) each. It consumed 3 kilowatts, about three times as much as today's microwave ovens, and was water-cooled. The name was the winning entry in an employee contest. 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 1954 consumed 1.6 kilowatts and sold for US$2,000 to US$3,000 ($ to $ in dollars). Raytheon licensed its technology to the Tappan Stove company of Mansfield, Ohio in 1952. They tried to market a large 220 volt wall unit as a home microwave oven in 1955 for a price of US$1,295 ($ in dollars), but it did not sell well.

Microwave oven

A microwave oven (also commonly referred to as a microwave) is an electric oven 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 of a homogeneous, high water content food item; food is more evenly heated throughout than generally occurs in other cooking techniques.

The development of the cavity magnetron in the UK made possible the production of electromagnetic waves of a small enough wavelength (microwaves). 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. Raytheon later licensed its patents for a home-use microwave oven that was first introduced by Tappan in 1955, but these units were still too large and expensive for general home use. Sharp Corporation introduced the first microwave oven with a turntable between 1964 and 1966. The countertop microwave oven was first introduced in 1967 by the Amana Corporation. After Sharp introduced low-cost microwave ovens affordable for residential use in the late 1970s, their use 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 a common kitchen appliance and are popular for reheating previously cooked foods and cooking a variety of foods. They are also useful for rapid heating of otherwise slowly prepared foodstuffs, which can easily burn or turn lumpy when cooked in conventional pans, such as hot butter, fats, chocolate or porridge. 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 limited roles in professional cooking, because the boiling-range temperatures of a microwave will not produce the flavorful chemical reactions that frying, browning, or baking at a higher temperature will. However, additional heat sources can be added to microwave ovens.

The exploitation of high-frequency radio waves for heating substances was made possible by the development of vacuum tube radio transmitters around 1920. By 1930 the application of short waves to heat human tissue had developed into the medical therapy of diathermy. At the 1933 Chicago World's Fair, Westinghouse demonstrated the cooking of foods between two metal plates attached to a 10 kW, 60 MHz shortwave transmitter. The Westinghouse team, led by I. F. Mouromtseff, found that foods like steaks and potatoes could be cooked in minutes.

The 1937 United States patent application by Bell Laboratories states:
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 10 to 20 megahertz (wavelength 15 to 30 meters). 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.

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. In 1937–1940, a multi-cavity magnetron was built by the 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 1940, at the University of Birmingham in England, Randall and Harry Boot produced a working prototype. They invented a valve that could spit out pulses of microwave radio energy on a wavelength of 10 cm, an unprecedented discovery.

Sir Henry Tizard travelled to the U.S. in late September 1940 to offer the magnetron in exchange for their financial and industrial help (see Tizard Mission). An early 6 kW version, built in England by the General Electric Company Research Laboratories, Wembley, London, was given to the U.S. government in September 1940. The magnetron was later described by American historian James Phinney Baxter III as "[t]he most valuable cargo ever brought to our shores". Contracts were awarded to Raytheon and other companies for mass production of the magnetron.

In 1945, the specific heating effect of a high-power microwave beam was accidentally discovered by 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 chocolate 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. 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 1945, 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.

Japan's Sharp Corporation began manufacturing microwave ovens in 1961. Between 1964 and 1966, Sharp introduced the first microwave oven with a turntable, a feature that promotes convenient even heating of food. In 1965, Raytheon acquired Amana. In 1967, they introduced the first popular home model, the countertop Radarange, at a price of US$495 ($ in dollars).

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: an empty microwave oven where there is nothing to absorb the microwaves. 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 U.S. industry in 1970 grew to one million by 1975. 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.

By 1972, Litton (Litton Atherton Division, Minneapolis) introduced two new microwave ovens, priced at $349 and $399, to tap into the market estimated at $750 million by 1976, according to Robert I Bruder, president of the division.
From the late 1970s, Japanese companies such as Sharp Corporation manufactured low-cost microwave ovens that were affordable for residential use, leading to the rapid expansion of the microwave oven market in the 1980s. After Japanese dominance for much of the 1980s, with Sharp as market leader, South Korean manufacturers began entering the market in the late 1980s, with Samsung becoming a major microwave manufacturer.

Formerly found only in large industrial applications, microwave ovens increasingly became a standard fixture of residential kitchens in developed countries. By 1986, roughly 25% of households in the U.S. owned a microwave oven, up from only about 1% in 1971; the U.S. Bureau of Labor Statistics reported that over 90% of American households owned a microwave oven in 1997. In Australia, a 2008 market research study found that 95% of kitchens contained a microwave oven and that 83% of them were used daily. In Canada, fewer than 5% of households had a microwave oven in 1979, but more than 88% of households owned one by 1998. In France, 40% of households owned a microwave oven in 1994, but that number had increased to 65% by 2004.

Adoption has been slower in less-developed countries, as households with disposable income concentrate on more important household appliances like refrigerators and ovens. In India, for example, only about 5% of households owned a microwave in 2013, well behind refrigerators at 31% ownership. However, microwave ovens are gaining popularity. In Russia, for example, the number of households with a microwave grew from almost 24% in 2002 to almost 40% in 2008. Almost twice as many households in South Africa owned microwaves in 2008 (38.7%) as in 2002 (19.8%). Microwave ownership in Vietnam was at 16% of households in 2008—versus 30% ownership of refrigerators; this rate was up significantly from 6.7% microwave ownership in 2002, with 14% ownership for refrigerators that year.

A microwave oven heats food by passing microwave radiation through it. Microwaves are a form of non-ionizing electromagnetic radiation with a frequency higher than ordinary radio waves but lower than infrared light. Microwave ovens use frequencies in one of the ISM (industrial, scientific, medical) bands, which are reserved for this use, so they do not interfere with other vital radio services. Consumer ovens usually use 2.45 gigahertz (GHz)— It is a wavelength of —while large industrial/commercial ovens often use 915 megahertz (MHz)—. 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 partial positive charge at one end and a partial negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. Rotating molecules hit other molecules and put them into motion, thus dispersing energy. This energy, dispersed as molecular rotations, vibrations and/or translations in solids and liquids raises the temperature of the food, in a process similar to heat transfer by contact with a hotter body It is a common misconception that microwave ovens heat food by operating at a special resonance of water molecules in the food. As noted microwave ovens can operate at many frequencies.

Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted. Dielectric heating of liquid water is also temperature-dependent: At 0 °C, dielectric loss is greatest at a field frequency of about 10 GHz, and for higher water temperatures at higher field frequencies.

Compared to liquid water, microwave heating is less efficient on fats and sugars (which have a smaller molecular dipole moment). Sugars and triglycerides (fats and oils) absorb microwaves due to the dipole moments of their hydroxyl groups or ester groups. However, due to the lower specific heat capacity of fats and oils and their higher vaporization temperature, they often attain much higher temperatures inside microwave ovens. This can induce temperatures in oil or very fatty foods like bacon far above the boiling point of water, and high enough to induce some browning reactions, much in the manner of conventional broiling (UK: grilling), braising, or deep fat frying. Foods high in water content and with little oil rarely exceed the boiling temperature of water.

Microwave heating can cause localized thermal runaways in some materials with low thermal conductivity which also have dielectric constants that increase with temperature. An example is glass, which can exhibit thermal runaway in a microwave to the point of melting if preheated. Additionally, microwaves can melt certain types of rocks, producing small quantities of molten rock. Some ceramics can also be melted, and may even become clear upon cooling. Thermal runaway is more typical of electrically conductive liquids such as salty water.

Another misconception is that microwave ovens cook food "from the inside out", meaning from the center of the entire mass of food outwards. This idea arises from heating behavior seen if an absorbent layer of water lies beneath a less absorbent drier layer at the surface of a food; in this case, the deposition of heat energy inside a food can exceed that on its surface. This can also occur if the inner layer has a lower heat capacity than the outer layer causing it to reach a higher temperature, or even if the inner layer is more thermally conductive than the outer layer making it feel hotter despite having a lower temperature. In most cases, however, with uniformly structured or reasonably homogenous food item, microwaves are absorbed in the outer layers of the item at a similar level to that of the inner layers. Depending on water content, the depth of initial heat deposition may be several centimetres or more with microwave ovens, in contrast to broiling/grilling (infrared) or convection heating—methods which deposit heat thinly at the food surface. Penetration depth of microwaves is dependent on food composition and the frequency, with lower microwave frequencies (longer wavelengths) penetrating further.

A microwave oven consists of:In most ovens, the magnetron is driven by a linear transformer which can only feasibly be switched completely on or off. (One variant of the GE Spacemaker had two taps on the transformer primary, for high and low power modes.) Usually choice of power level doesn't affect intensity of the microwave radiation; instead, the magnetron is cycled on and off every few seconds, thus altering the large scale duty cycle. Newer models use "inverter" power supplies that use pulse-width modulation to provide effectively continuous heating at reduced power settings, so that foods are heated more evenly at a given power level and can be heated more quickly without being damaged by uneven heating.

The microwave frequencies used in microwave ovens are chosen based on regulatory and cost constraints. The first is that they should be in one of the industrial, scientific, and medical (ISM) frequency bands set aside for unlicensed purposes. For household purposes, 2.45 GHz has the advantage over 915 MHz in that 915 MHz is only an ISM band in the ITU Region 2 while 2.45 GHz is available worldwide. Three additional ISM bands exist in the microwave frequencies, but are not used for microwave cooking. Two of them are centered on 5.8 GHz and 24.125 GHz, but are not used for microwave cooking because of the very high cost of power generation at these frequencies. The third, centered on 433.92 MHz, is a narrow band that would require expensive equipment to generate sufficient power without creating interference outside the band, and is only available in some countries.

The cooking chamber is similar to a Faraday cage to prevent the waves from coming out of the oven. Even though there is no continuous metal-to-metal contact around the rim of the door, choke connections on the door edges act like metal-to-metal contact, at the frequency of the microwaves, to prevent leakage. The oven door usually has a window for easy viewing, with a layer of conductive mesh some distance from the outer panel to maintain the shielding. Because the size of the perforations in the mesh is much less than the microwaves' wavelength (12.2 cm for the usual 2.45 GHz), microwave radiation cannot pass through the door, while visible light (with its much shorter wavelength) can.

Modern microwave ovens use either an analog dial-type timer or a digital control panel for operation. Control panels feature an LED, liquid crystal or vacuum fluorescent display, in the 90s brands such as Panasonic and GE began offering models with a scrolling-text display showing cooking instructions, numeric buttons for entering the cook time, a power level selection feature and other possible functions such as a defrost setting and pre-programmed settings for different food types, such as meat, fish, poultry, vegetables, frozen vegetables, frozen dinners, and popcorn.

Power settings are commonly implemented, not by actually varying the effect, but by repeatedly turning the power off and on. The highest setting thus represents continuous power. Defrost might represent power for two seconds followed by no power for five seconds. An audible warning such as a bell or a beeper is usually present to indicate that cooking has completed.

Microwave control panels are often considered awkward to use and are frequently employed as examples for user interface design.

A variant of the conventional microwave is the convection microwave. A convection microwave oven 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 conventional microwave ovens. Some convection microwaves—those with exposed heating elements—can produce smoke and burning odors as food spatter from earlier microwave-only use is burned off the heating elements.

In 2000, some manufacturers began offering high power quartz halogen bulbs to their convection microwave models, marketing them under names such as "Speedcook", "Advantium", "Lightwave" and "Optimawave" to emphasize their ability to cook food rapidly and with good browning. The bulbs heat the food's surface with infrared (IR) radiation, browning surfaces as in a conventional oven. The food browns while also being heated by the microwave radiation and heated through conduction through contact with heated air. The IR energy which is delivered to the outer surface of food by the lamps is sufficient to initiate browning caramelization in foods primarily made up of carbohydrates and Maillard reactions in foods primarily made up of protein. These reactions in food produce a texture and taste similar to that typically expected of conventional oven cooking rather than the bland boiled and steamed taste that microwave-only cooking tends to create.

In order to aid browning, sometimes an accessory browning tray is used, usually composed of glass or porcelain. It makes food crisp by oxidizing the top layer until it turns brown. Ordinary plastic cookware is unsuitable for this purpose because it could melt.

Frozen dinners, pies, and microwave popcorn bags often contain a susceptor made from thin aluminium film in the packaging or included on a small paper tray. The metal film absorbs microwave energy efficiently and consequently becomes extremely hot and radiates in the infrared, concentrating the heating of oil for popcorn or even browning surfaces of frozen foods. Heating packages or trays containing susceptors are designed for a single use and are then discarded as waste.

Microwave ovens produce heat directly within the food, but despite the common misconception that microwaved food cooks from the inside out, 2.45 GHz microwaves can only penetrate approximately into most foods. The inside portions of thicker foods are mainly heated by heat conducted from the outer.

Uneven heating in microwaved food can be 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 location of dead spots and hot spots in a microwave can be mapped out by placing a damp piece of thermal paper in the oven. When the water saturated paper is subjected to the microwave radiation it becomes hot enough to cause the dye to be released which will provide a visual representation of the microwaves. If multiple layers of paper are constructed in the oven with a sufficient distance between them a three-dimensional map can be created. Many store receipts are printed on thermal paper which allows this to be easily done at home.

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. Under certain conditions, glass can exhibit thermal runaway in a microwave to the point of melting.

Due to this phenomenon, microwave ovens set at too-high power levels may even start to cook the edges of 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 cannot dissipate the heat due to the low thermal conductivity of the bread. Often this results in overheating the berries relative to the rest of the food. "Defrost" oven settings either use low power levels or turn the power off and on repeatedly - designed to allow time for heat to be conducted within frozen foods from areas that absorb heat more readily to those which heat more slowly. In turntable-equipped ovens, more even heating will take place by placing food off-centre on the turntable tray instead of exactly in the centre, so that no part of the food item will be continuously unheated by the center "dead zone".

There are microwave ovens on the market that allow full-power defrosting. They do this by exploiting the properties of the electromagnetic radiation LSM modes. LSM full-power defrosting may actually achieve more even results than slow defrosting.

Microwave heating can be deliberately uneven by design. Some microwavable packages (notably pies) may include materials that contain ceramic or aluminium flakes, which are designed to absorb microwaves and heat up, which aids in baking or crust preparation by depositing more energy shallowly in these areas. Such ceramic patches affixed to cardboard are positioned next to the food, and are typically smokey blue or gray in colour, usually making them easily identifiable; the cardboard sleeves included with Hot Pockets, which have a silver surface on the inside, are a good example of such packaging. 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.

Any form of cooking will destroy some nutrients in food, but the key variables are how much water is used in the cooking, how long the food is cooked, and at what temperature. Nutrients are primarily lost by leaching into cooking water, which tends to make microwave cooking healthier, given the shorter cooking times it requires. Like other heating methods, microwaving converts vitamin B from an active to inactive form; the amount of conversion depends on the temperature reached, as well as the cooking time. Boiled food reaches a maximum of (the boiling point of water), whereas microwaved food can get locally hotter than this, leading to faster breakdown of vitamin B. The higher rate of loss is partially offset by the shorter cooking times required.

Spinach retains nearly all its folate when cooked in a microwave; in comparison, it loses about 77% when boiled, leaching out nutrients. Bacon cooked by microwave has significantly lower levels of carcinogenic nitrosamines than conventionally cooked bacon. Steamed vegetables tend to maintain more nutrients when microwaved than when cooked on a stovetop. Microwave blanching is 3–4 times more effective than boiled water blanching in the retaining of the water-soluble vitamins folic acid, thiamin and riboflavin, with the exception of ascorbic acid, of which 28.8% is lost (vs. 16% with boiled water blanching).

Microwaving human milk at high temperatures is not recommended as it causes a marked decrease in activity of anti-infective factors.

All microwaves use a timer for the cooking time, at the end of cooking time, the oven switches itself off.

Microwave ovens heat food without getting hot themselves. Taking a pot off a stove, unless it is 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.

Food and cookware taken out of a microwave oven are rarely much hotter than. Cookware used in a microwave oven is often much cooler than the food because the cookware is transparent to microwaves; the microwaves heat the food directly and the cookware is indirectly 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. 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 burn 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. Unlike frying and baking, microwaving does not produce acrylamide in potatoes, however unlike deep-frying, it is of only limited effectiveness in reducing glycoalkaloid (i.e., solanine) levels. Acrylamide has been found in other microwaved products like popcorn.

Studies have investigated the use of the microwave to clean non-metallic domestic sponges which have been thoroughly wetted. A 2006 study found that microwaving wet sponges for two minutes (at 1000 watt power) removed 99% of coliforms, "E. coli" and MS2 phages. "Bacillus cereus" spores were killed at four minutes of microwaving.

A 2017 study was less affirmative: about 60% of the germs were killed but the remaining ones quickly re-colonized the sponge.

Water and other homogeneous liquids can superheat when heated in a microwave oven in a container with a smooth surface. That is, the liquid reaches a temperature slightly above its normal boiling point without bubbles of vapour forming inside the liquid. The boiling process can start explosively when the liquid is disturbed, such as when the user takes hold of the container to remove it from the oven or while adding solid ingredients such as powdered creamer or sugar. This can result in spontaneous boiling (nucleation) which may be violent enough to eject the boiling liquid from the container and cause severe scalding.

Closed containers, such as eggs, can explode when heated in a microwave oven due to the increased pressure from steam. Intact fresh egg yolks outside the shell will also explode, as a result of superheating. Insulating plastic foams of all types generally contain closed air pockets, and are generally not recommended for use in a microwave, as the air pockets explode and the foam (which can be toxic if consumed) may melt. Not all plastics are microwave-safe, and some plastics absorb microwaves to the point that they may become dangerously hot.

Products that are heated for too long can catch fire. Though this is inherent to any form of cooking, the rapid cooking and unattended nature of the use of microwave ovens results in additional hazard.

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, and is sometimes utilized for cooking.

Any object containing pointed metal can create an electric arc (sparks) when microwaved. This includes cutlery, crumpled aluminium foil (though some foil used in microwaves are safe, see below), twist-ties containing metal wire, the metal wire carry-handles in paper Chinese take-out food containers, or almost any metal formed into a poorly conductive foil or thin wire; or into a pointed shape. Forks are a good example: the tines of the fork respond to the electric field by producing high concentrations of electric charge at the tips. This has the effect of exceeding the dielectric breakdown of air, about 3 megavolts per meter (3×10 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. When dielectric breakdown occurs in air, some ozone and nitrogen oxides are formed, both of which are unhealthy in large quantities.

It is possible for metal objects to be microwave-oven compatible, although experimentation by users is not encouraged. Microwaving an individual smooth metal object without pointed ends, for example, a spoon or shallow metal pan, usually does not produce sparking. Thick metal wire racks can be part of the interior design in microwave ovens (see illustration). In a similar way, the interior wall plates with perforating holes which allow light and air into the oven, and allow interior-viewing through the oven door, are all made of conductive metal formed in a safe shape.
The effect of microwaving thin metal films can be seen clearly on a Compact Disc or DVD (particularly the factory pressed type). The microwaves induce electric currents in the metal film, which heats up, melting the plastic in the disc and leaving a visible pattern of concentric and radial scars. Similarly, porcelain with thin metal films can also be destroyed or damaged by microwaving. Aluminium foil is thick enough to be used in microwave ovens as a shield against heating parts of food items, if the foil is not badly warped. When wrinkled, aluminium foil is generally unsafe in microwaves, as manipulation of the foil causes sharp bends and gaps that invite sparking. The USDA recommends that aluminium foil used as a partial food shield in microwave cooking cover no more than one quarter of a food object, and be carefully smoothed to eliminate sparking hazards.

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 overload and burn out. High reflected power may also cause magnetron arcing, possibly resulting in primary power fuse failure, though such a causal relationship isn't easily established. Thus, dehydrated food, or food wrapped in metal which does not arc, is problematic for overload reasons, without necessarily being a fire hazard.

Certain foods such as grapes, if properly arranged, can produce an electric arc. Prolonged arcing from food carries similar risks to arcing from other sources as noted above.

Some other objects that may conduct sparks are plastic/holographic print thermoses (such as Starbucks novelty cups) or cups with metal lining. If any bit of the metal is exposed, all the outer shell will burst off the object or melt.

The high electrical fields generated inside a microwave often can be illustrated by placing a radiometer or neon glow-bulb inside the cooking chamber, creating glowing plasma inside the low-pressure bulb of the device.

Direct microwave exposure is not generally possible, as microwaves emitted by the source in a microwave oven are confined in the oven by the material out of which the oven is constructed. Furthermore, ovens are equipped with redundant safety interlocks, which remove power from the magnetron if the door is opened. This safety mechanism is required by United States federal regulations. Tests have shown confinement of the microwaves in commercially available ovens to be so nearly universal as to make routine testing unnecessary. According to the United States Food and Drug Administration's Center for Devices and Radiological Health, a U.S. Federal Standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts of microwave radiation per square centimeter at approximately (2 in) from the surface of the oven. This is far below the exposure level currently considered to be harmful to human health.

The radiation produced by a microwave oven is non-ionizing. It therefore does not have the cancer risks associated with ionizing radiation such as X-rays and high-energy particles. Long-term rodent studies to assess cancer risk have so far failed to identify any carcinogenicity from microwave radiation even with chronic exposure levels (i.e. large fraction of life span) far larger than humans are likely to encounter from any leaking ovens. However, with the oven door open, the radiation may cause damage by heating. Every microwave oven sold has a protective interlock so that it cannot be run when the door is open or improperly latched.

Microwaves generated in microwave ovens cease to exist once the electrical power is turned off. They do not remain in the food when the power is turned off, any more than light from an electric lamp remains in the walls and furnishings of a room when the lamp is turned off. They do not make the food or the oven radioactive. Compared to conventional cooking, the nutritional content of some foods may be altered differently, but generally in a positive way by preserving more micronutrients - see above. There is no indication of detrimental health issues associated with microwaved food.

There are, however, a few cases where people have been exposed to direct microwave radiation, either from appliance malfunction or deliberate action. The general effect of this exposure will be physical burns to the body, as human tissue, particularly the outer fat and muscle layers, has similar composition to some foods that are typically cooked in microwave ovens and so experiences similar dielectric heating effects when exposed to microwave electromagnetic radiation.

Some magnetrons have ceramic insulators with beryllium oxide (beryllia) added. The beryllium in such oxides is a serious chemical hazard if crushed then inhaled or ingested. In addition, beryllia is listed as a confirmed human carcinogen by the IARC; therefore, broken ceramic insulators or magnetrons should not be handled. This is a danger if the microwave oven becomes physically damaged, if the insulator cracks, or when the magnetron is opened and handled, yet not during normal usage.
The use of unmarked plastics for microwave cooking raises the issue of plasticizers leaching into the food, or the plastics chemically reacting to microwave energy, with by-products leaching into the food, suggesting that even plastic containers marked "microwavable" may still leach plastic by-products into the food.

The plasticizers which received the most attention are bisphenol A (BPA) and phthalates, although it is unclear whether other plastic components present a toxicity risk. Other issues include melting and flammability. An alleged issue of release of dioxins into food has been dismissed as an intentional red herring distraction from actual safety issues.

Some current plastic containers and food wraps are specifically designed to resist radiation from microwaves. Products may use the term "microwave safe", may carry a microwave symbol (three lines of waves, one above the other) or simply provide instructions for proper microwave use. Any of these is an indication that a product is suitable for microwaving when used in accordance with the directions provided.

Microwave ovens are frequently used for reheating leftover food, and bacterial contamination may not be repressed if the safe temperature is not reached, resulting in foodborne illness, as with all inadequate reheating methods. While microwaves can destroy bacteria as well as conventional ovens, they do not cook as evenly, leading to an increased risk that parts of the food will not reach recommended temperatures.

Microwave ovens, although shielded for safety purposes, still emit low levels of microwave radiation. This is not harmful to humans, but can sometimes cause interference to Wi-Fi and Bluetooth and other devices that communicate on the 2.45 GHz wavebands; particularly at close range.

Japan's Sharp Corporation began manufacturing microwave ovens in 1961. Between 1964 and 1966, Sharp introduced the first microwave oven with a turntable, a feature that promotes convenient even heating of food. In 1965, Raytheon acquired Amana. In 1967, they introduced the first popular home model, the countertop Radarange, at a price of US$495 ($ in dollars).

Microwave oven

A microwave oven (also commonly referred to as a microwave) is an electric oven 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 of a homogeneous, high water content food item; food is more evenly heated throughout than generally occurs in other cooking techniques.

Microwave ovens have limited roles in professional cooking, because the boiling-range temperatures of a microwave will not produce the flavorful chemical reactions that frying, browning, or baking at a higher temperature will. However, additional heat sources can be added to microwave ovens.

The exploitation of high-frequency radio waves for heating substances was made possible by the development of vacuum tube radio transmitters around 1920. By 1930 the application of short waves to heat human tissue had developed into the medical therapy of diathermy. At the 1933 Chicago World's Fair, Westinghouse demonstrated the cooking of foods between two metal plates attached to a 10 kW, 60 MHz shortwave transmitter. The Westinghouse team, led by I. F. Mouromtseff, found that foods like steaks and potatoes could be cooked in minutes.

Sir Henry Tizard travelled to the U.S. in late September 1940 to offer the magnetron in exchange for their financial and industrial help (see Tizard Mission). An early 6 kW version, built in England by the General Electric Company Research Laboratories, Wembley, London, was given to the U.S. government in September 1940. The magnetron was later described by American historian James Phinney Baxter III as "[t]he most valuable cargo ever brought to our shores". Contracts were awarded to Raytheon and other companies for mass production of the magnetron.

Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted. Dielectric heating of liquid water is also temperature-dependent: At 0 °C, dielectric loss is greatest at a field frequency of about 10 GHz, and for higher water temperatures at higher field frequencies.

Microwave heating can cause localized thermal runaways in some materials with low thermal conductivity which also have dielectric constants that increase with temperature. An example is glass, which can exhibit thermal runaway in a microwave to the point of melting if preheated. Additionally, microwaves can melt certain types of rocks, producing small quantities of molten rock. Some ceramics can also be melted, and may even become clear upon cooling. Thermal runaway is more typical of electrically conductive liquids such as salty water.

Modern microwave ovens use either an analog dial-type timer or a digital control panel for operation. Control panels feature an LED, liquid crystal or vacuum fluorescent display, in the 90s brands such as Panasonic and GE began offering models with a scrolling-text display showing cooking instructions, numeric buttons for entering the cook time, a power level selection feature and other possible functions such as a defrost setting and pre-programmed settings for different food types, such as meat, fish, poultry, vegetables, frozen vegetables, frozen dinners, and popcorn.

Power settings are commonly implemented, not by actually varying the effect, but by repeatedly turning the power off and on. The highest setting thus represents continuous power. Defrost might represent power for two seconds followed by no power for five seconds. An audible warning such as a bell or a beeper is usually present to indicate that cooking has completed.

Microwave control panels are often considered awkward to use and are frequently employed as examples for user interface design.

A variant of the conventional microwave is the convection microwave. A convection microwave oven 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 conventional microwave ovens. Some convection microwaves—those with exposed heating elements—can produce smoke and burning odors as food spatter from earlier microwave-only use is burned off the heating elements.

In order to aid browning, sometimes an accessory browning tray is used, usually composed of glass or porcelain. It makes food crisp by oxidizing the top layer until it turns brown. Ordinary plastic cookware is unsuitable for this purpose because it could melt.

Frozen dinners, pies, and microwave popcorn bags often contain a susceptor made from thin aluminium film in the packaging or included on a small paper tray. The metal film absorbs microwave energy efficiently and consequently becomes extremely hot and radiates in the infrared, concentrating the heating of oil for popcorn or even browning surfaces of frozen foods. Heating packages or trays containing susceptors are designed for a single use and are then discarded as waste.

Microwave ovens produce heat directly within the food, but despite the common misconception that microwaved food cooks from the inside out, 2.45 GHz microwaves can only penetrate approximately into most foods. The inside portions of thicker foods are mainly heated by heat conducted from the outer.

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. Under certain conditions, glass can exhibit thermal runaway in a microwave to the point of melting.

There are microwave ovens on the market that allow full-power defrosting. They do this by exploiting the properties of the electromagnetic radiation LSM modes. LSM full-power defrosting may actually achieve more even results than slow defrosting.

Microwaving human milk at high temperatures is not recommended as it causes a marked decrease in activity of anti-infective factors.

All microwaves use a timer for the cooking time, at the end of cooking time, the oven switches itself off.

Microwave ovens heat food without getting hot themselves. Taking a pot off a stove, unless it is 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.

Food and cookware taken out of a microwave oven are rarely much hotter than. Cookware used in a microwave oven is often much cooler than the food because the cookware is transparent to microwaves; the microwaves heat the food directly and the cookware is indirectly 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. That means that conventional stoves and ovens can cause more serious burns.

Studies have investigated the use of the microwave to clean non-metallic domestic sponges which have been thoroughly wetted. A 2006 study found that microwaving wet sponges for two minutes (at 1000 watt power) removed 99% of coliforms, "E. coli" and MS2 phages. "Bacillus cereus" spores were killed at four minutes of microwaving.

A 2017 study was less affirmative: about 60% of the germs were killed but the remaining ones quickly re-colonized the sponge.

Closed containers, such as eggs, can explode when heated in a microwave oven due to the increased pressure from steam. Intact fresh egg yolks outside the shell will also explode, as a result of superheating. Insulating plastic foams of all types generally contain closed air pockets, and are generally not recommended for use in a microwave, as the air pockets explode and the foam (which can be toxic if consumed) may melt. Not all plastics are microwave-safe, and some plastics absorb microwaves to the point that they may become dangerously hot.

Products that are heated for too long can catch fire. Though this is inherent to any form of cooking, the rapid cooking and unattended nature of the use of microwave ovens results in additional hazard.

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, and is sometimes utilized for cooking.

Certain foods such as grapes, if properly arranged, can produce an electric arc. Prolonged arcing from food carries similar risks to arcing from other sources as noted above.

Some other objects that may conduct sparks are plastic/holographic print thermoses (such as Starbucks novelty cups) or cups with metal lining. If any bit of the metal is exposed, all the outer shell will burst off the object or melt.

The high electrical fields generated inside a microwave often can be illustrated by placing a radiometer or neon glow-bulb inside the cooking chamber, creating glowing plasma inside the low-pressure bulb of the device.

Microwaves generated in microwave ovens cease to exist once the electrical power is turned off. They do not remain in the food when the power is turned off, any more than light from an electric lamp remains in the walls and furnishings of a room when the lamp is turned off. They do not make the food or the oven radioactive. Compared to conventional cooking, the nutritional content of some foods may be altered differently, but generally in a positive way by preserving more micronutrients - see above. There is no indication of detrimental health issues associated with microwaved food.

There are, however, a few cases where people have been exposed to direct microwave radiation, either from appliance malfunction or deliberate action. The general effect of this exposure will be physical burns to the body, as human tissue, particularly the outer fat and muscle layers, has similar composition to some foods that are typically cooked in microwave ovens and so experiences similar dielectric heating effects when exposed to microwave electromagnetic radiation.

The plasticizers which received the most attention are bisphenol A (BPA) and phthalates, although it is unclear whether other plastic components present a toxicity risk. Other issues include melting and flammability. An alleged issue of release of dioxins into food has been dismissed as an intentional red herring distraction from actual safety issues.

Some current plastic containers and food wraps are specifically designed to resist radiation from microwaves. Products may use the term "microwave safe", may carry a microwave symbol (three lines of waves, one above the other) or simply provide instructions for proper microwave use. Any of these is an indication that a product is suitable for microwaving when used in accordance with the directions provided.

Microwave ovens are frequently used for reheating leftover food, and bacterial contamination may not be repressed if the safe temperature is not reached, resulting in foodborne illness, as with all inadequate reheating methods. While microwaves can destroy bacteria as well as conventional ovens, they do not cook as evenly, leading to an increased risk that parts of the food will not reach recommended temperatures.

Microwave ovens, although shielded for safety purposes, still emit low levels of microwave radiation. This is not harmful to humans, but can sometimes cause interference to Wi-Fi and Bluetooth and other devices that communicate on the 2.45 GHz wavebands; particularly at close range.

Raytheon filed a patent on October 8, 1945 for a microwave cooking oven, eventually named the Radarange. In 1947, the first commercially produced microwave oven was about 6 feet tall, weighed about 750 lbs, and cost about 5,000 US$. In 1967 the first relatively affordable ($495) and reasonably sized (counter-top) microwave oven was available for sale.

Percy Spencer

Percy Lebaron Spencer (July 19, 1894 – September 8, 1970) was an American physicist and inventor. He became known as the inventor of the microwave oven.

Spencer was born in Howland, Maine. Eighteen months later, Spencer's father died, and his mother soon left him in the care of his aunt and uncle. His uncle then died when Spencer was just seven years old. Spencer subsequently left grammar school to earn money to support himself and his aunt. From the ages of twelve to sixteen, he worked from sunrise to sunset at a spool mill. At the later age, he discovered that a local paper mill was soon to begin using electricity, a concept little known in his rural home region, and he accordingly began learning as much as possible about the phenomenon. Therefore, when he applied to work at the mill, he was one of three people hired to install electricity in the plant, despite never having received any formal training in electrical engineering or even finishing grammar school. At the age of 18, Spencer decided to join the U.S. Navy. He had become interested in wireless communications after learning about the wireless operators aboard the Titanic when it sank. While with the navy, he made himself an expert on radio technology: "I just got hold of a lot of textbooks and taught myself while I was standing watch at night." He also subsequently taught himself trigonometry, calculus, chemistry, physics, and metallurgy, among other subjects.

By 1939 Spencer became one of the world’s leading experts in radar tube design. Spencer worked at Raytheon, a contractor for the U.S. Department of Defense, as the chief of the power tube division. Largely due to his reputation and expertise, Spencer managed to help Raytheon win a government contract to develop and produce combat radar equipment for M.I.T.’s Radiation Laboratory. This was of huge importance to the Allies and became the military’s second highest priority project during WWII, behind the Manhattan Project. At that time, magnetrons were used to generate the microwave radio signals that are the core mechanism of radar, and they were being made at the rate of 17 per day at Raytheon. While working there, Spencer developed a more efficient way to manufacture them, by punching out and soldering together magnetron parts, rather than using machined parts. It also saw Spencer’s staff rise from 15 employees to 5,000 over the course of the next few years. His improvements were among those that increased magnetron production to 2,600 per day. For his work, he was awarded the Distinguished Public Service Award by the U.S. Navy.

One day while building magnetrons, Spencer was standing in front of an active radar set when he noticed the candy bar he had in his pocket had melted. Spencer was not the first to notice this phenomenon, but he was the first to investigate it. He decided to experiment using food, including popcorn kernels, which became the world’s first microwaved popcorn. In another experiment, an egg was placed in a tea kettle, and the magnetron was placed directly above it. The result was the egg exploding in the face of one of his co-workers, who was looking in the kettle to observe. Spencer then created the first true microwave oven by attaching a high density electromagnetic field generator to an enclosed metal box. The magnetron emitted microwaves into the metal box blocking any escape, allowing for controlled and safe experimentation. He then placed various food items in the box, while observing effects and monitoring temperatures.

Spencer became Senior Vice President and a Senior Member of the Board of Directors at Raytheon. He received 300 patents during his career, and a building at the Raytheon Missile Defense Center in Burlington, Massachusetts is named in his honor. Other achievements and awards, besides the Distinguished Public Service Award, included a membership of the Institute of Radio Engineers, Fellowship in the American Academy of Arts and Sciences, and an honorary Doctor of Science from the University of Massachusetts, despite having no formal education.

For his invention, Spencer received no royalties, but he was paid a one-time $2.00 gratuity from Raytheon, the same token payment the company made to all inventors on its payroll at that time for company patents.

Spencer and his wife, Louise, had three children: John, James, and George. He counted Vannevar Bush, Omar Bradley, William Redington Hewlett and David Packard as friends. Later, he was married to Lillian Ottenheimer on November 18, 1960.

Raytheon Integrated Defense Systems, which deals extensively in radar systems, has named a building after Spencer in the Woburn, Massachusetts facility. An early Radarange model sits in the lobby, across from the dining center.


Is The Thick of It on-going?

The Thick of It is a British comedy television series that satirises the inner workings of modern British government. It was first broadcast for two short series on BBC Four in 2005, initially with a small cast focusing on a government minister, his advisers and their party's spin-doctor. The cast was significantly expanded for two hour-long specials to coincide with Christmas and Gordon Brown's appointment as prime minister in 2007, which saw new characters forming the opposition party added to the cast. These characters continued when the show switched channels to BBC Two for its third series in 2009. A fourth series about a coalition government was broadcast in 2012, with the last episode transmitted on 27 October 2012. In a 2012 interview, series creator Armando Iannucci said the fourth series of the programme would probably be its last.

The Thick of It

The series has been described as the 21st century's answer to "Yes Minister", highlighting the struggles and conflicts between politicians, party spin doctors, advisers, civil servants and the media. As with "Yes Minister", the political parties involved are never mentioned by name, although the context makes clear which is which. Iannucci describes it as ""Yes Minister" meets "Larry Sanders"". The journalist and former civil servant Martin Sixsmith is an adviser to the writing team, adding to the realism of some scenes. The series became well known for its profanity and for featuring storylines which have mirrored, or in some cases predicted real-life policies, events or scandals.

A feature film spin-off, "In the Loop", was released in the UK on 17 April 2009. A pilot for a U.S. remake of the show was not successful, but Iannucci was subsequently invited to create "Veep" for HBO, a programme with a very similar tone and political issues, with the involvement of some "The Thick of It" writers and production members.

Armando Iannucci originally conceived of a modern political satire after "arguing the case" for "Yes Minister" in a 2004 Best British Sitcom poll for BBC Two. His idea was commissioned by Roly Keating, the controller of BBC Four, who granted Iannucci limited budget, telling him to "turn that into what you can." Iannucci created the first series of three episodes, which aired in May–June 2005, and a second series, also of three episodes, which followed in October.

The series is written by a team of writers led by Armando Iannucci, who also directs the series, with Jesse Armstrong, Simon Blackwell, Roger Drew, Sean Gray, Ian Martin, Will Smith and Tony Roche. Some of the dialogue is improvised rather than scripted (with the cast credited as providing "additional material"), and includes some very strong language. Peter Capaldi said "Fundamentally 80% of the final cut is the script that we started with. The improvisation just makes it feel more real and not written." Prior to rehearsals, the scripts are sent to a "swearing consultant" in Lancaster called Ian Martin, who adds some of the more colourful language. The programme's producer is Adam Tandy, who has produced all of Iannucci's television projects since 2000. The programme is shot with hand-held cameras to give it a sense of vérité or fly-on-the-wall documentary. The documentary style is furthered by the absence of any incidental music or laughter track.

The action centres on the fictional Department of Social Affairs and Citizenship ("DoSAC" – previously the Department of Social Affairs, or "DSA", prior to the reshuffle of episode five), which supposedly came out of the prime minister's passing enthusiasm for "joined-up government". Thus it acts as a "super department" overseeing many others, with some similarities to the Cabinet Office. This concept enables different political themes to be dealt with in the programme, similar to the Department of Administrative Affairs in "Yes Minister".

Hugh Abbot, played by Chris Langham, is a blundering minister heading the department, who is continually trying to do his job under the watchful eye of Malcolm Tucker (Peter Capaldi), Number 10's highly aggressive and domineering "enforcer". The programme also features James Smith as senior special adviser Glenn Cullen, Chris Addison as junior policy adviser Ollie Reeder, and Joanna Scanlan as civil service press secretary Terri Coverley.

The series was revamped for the third series with Hugh Abbot being replaced as head of DoSAC by Nicola Murray (Rebecca Front), who arrives without her own staff, so Ollie and Glenn find themselves keeping their jobs.

From series 4, after a general election which results in a coalition government, Peter Mannion MP (Roger Allam) is new Secretary of State for DoSAC, supported by his team of special advisers, commanded by Number 10's Director of Communications Stewart Pearson (Vincent Franklin) and thwarted by his new coalition partner, DoSAC's junior minister Fergus Williams MP (Geoffrey Streatfeild). Nicola Murray MP is now leader of the opposition, and opposition spin doctor Malcolm Tucker is desperate for a return to power.

Even though no mention is made of the words "Labour", "Conservative" and "Liberal Democrat", it is strongly implied throughout the four series that this is a dramatised reflection of real-life political parties and events rather than a parallel universe. Each political party is portrayed in equally unflattering terms, each being shown as inept, accident-prone and generally inefficient, and each having their own unique problems. For instance, the ruling party of the first three seasons, to which Abbot and Murray belong, is portrayed as being hampered by its many warring factions and internal strife, which reflects the real-life factionalism and power struggles within the Labour Party both during and after Tony Blair's leadership and the rise to power of Gordon Brown's faction (roughly identified as the "Nutters" in the series), as well as its pragmatic approach to politics. On the other side, the Opposition party to which Mannion belongs is portrayed as suffering from an image problem, being seen as backward, old-fashioned and unprogressive, and having a relatively young, inexperienced leader running a PR overhaul to broaden the party's appeal – a reference to the then Conservative Party leader David Cameron, whose attention to image in his early years of leadership was often derided both inside and outside his party. Additionally, the smaller coalition party of which Fergus Williams is a member is portrayed as having similar principles to Murray's party, and is widely accused of having betrayed its own principles by entering into a coalition with Mannion's party, referencing similar accusations made against the Liberal Democrats after the 2010 coalition was formed. Most parallels are drawn from personal conversations between characters, rather than actual policies, however – indeed, most of the actual policies that are seen being implemented are quite mundane, and have no political or ideological significance.

For instance, there is an underlying bitterness between Dan Miller and Nicola Murray in the fourth season because Murray reportedly won leadership on a "technicality," despite not having the leadership material that Miller has, a reference to the events of the 2010 Labour leadership election, which saw Ed Miliband become leader over his brother, David, which likewise came down to a technicality in the voting procedure. Throughout the series, Mannion's party is linked by Malcolm and his co-workers to snobbishness, emotional suppression, upper-class institutions such as Eton College. On another occasion, Mannion – who, though fairly moderate compared to others within his party, is nevertheless a member of the "old guard" - complains to Stewart Pearson about the hypocrisy of the Leader of the Opposition and his "Eton clique" who are ostensibly trying to modernise their party by expelling its bigoted and old-fashioned members while routinely texting each other racist jokes in private. Upon being fired, Pearson sums up his time in the party by remarking that his efforts to modernise the party by fixing the undesirable views of its members made no difference to the inherent issues that went to its foundations. In the fourth season, Glenn Cullen is often seen to complain to Terri and Ollie about Fergus's willingness to throw his lot in with a party whose policies vastly contradicted their own, having left his original party because of disillusionment with their political pragmatism. Perhaps the clearest indication of the real-life basis for the fictional parties and events is a comment by Phil Smith, who belongs to Mannion's party: "... a lot of good things came out of the 80s: (…) deregulation of the stock exchange, "us being in power"...". The mainstream media and general public are commonly portrayed in equally unflattering terms, being portrayed as aggressively hounding politicians and asking awkward, often outrageous questions, or otherwise being discourteous and harsh.

In the first batch of three episodes, Hugh Abbot is installed as a new minister following the forced resignation of his predecessor Cliff Lawton. These episodes follow his attempts to make his mark on the department by introducing new policies while following the party line enforced by Malcolm Tucker. Due to a series of complications and mistakes, this leads to the minister coming close to resignation on a number of occasions.

The second batch of episodes takes place before a cabinet reshuffle, and follows Hugh's attempts to keep his job. Ollie Reeder is seconded to number 10 "to phone his girlfriend" Emma Messinger, a member of the shadow defence policy team, where he is under the close eye of enforcer Jamie. Meanwhile, Terri Coverley is on compassionate leave following the death of her father, leaving her role to Robyn Murdoch, a senior press officer. The department also has to contend with the interference of the prime minister's "blue skies" adviser Julius Nicholson. The minister and the department survive the reshuffle, with the department being rebranded as the "Department of Social Affairs and Citizenship" and moved to a new building. However, the mistakes and compromises continue.

In the two specials, following the Christmas break, Hugh Abbot is in Australia and the department has to "babysit" junior minister for immigration Ben Swain, who is described as a "Nutter" (a term used for supporters of prime-minister-in-waiting Tom Davis). The first special ("Rise of the Nutters") revolves around a computer problem at Immigration, which is exacerbated by the junior minister appearing in a disastrous "Newsnight" interview. The opposition policy adviser Emma Messinger capitalises on the error by stealing an idea from her boyfriend Ollie Reeder, to send the shadow minister Peter Mannion on a fact-finding mission at an immigration centre. Meanwhile, Tucker is concerned about his position in the government after speculating that the prime minister's handover to Tom Davis is expected in less than six months. Tucker conspires with Ollie to leak the prime minister's "legacy programme" (the PM's plan to move the handling of immigration policy to a non-political executive board) in the hope of stalling his departure, inadvertently leading the PM to resign early. The next episode ("Spinners and Losers") follows a single night of "spin", as advisers, junior politicians and enforcers all try to better their position during the transition, but only Malcolm gets anywhere.

In series 3, Hugh Abbot is replaced as minister by Nicola Murray, played by Rebecca Front. She is an unexpected, last-minute choice for the position, and given her inexperience and lack of staff, she is forced to retain Ollie and Glenn as her advisers. The series continues to focus on the general running, or mis-running, of DoSAC, with Murray's attempts to formulate her "Fourth Sector Pathfinder Initiative" being a running thread throughout the series. With the cloud of the forthcoming general election and tension at 10 Downing Street looming, the series also broadens its scope to include episodes set at the annual party conference and BBC Radio 5 Live. We also see more of Murray's opposite number, Peter Mannion, and other members of the opposition first seen in the 2007 specials. The gradual breakdown of Malcolm Tucker and appearance of new threats to his control, in particular Steve Fleming (David Haig), are also major plotlines. The series ends with Fleming forcing Malcolm's resignation, only to be ousted himself a matter of days later. Having regained dominance, Malcolm decides to call an election immediately to seize the initiative from his enemies in the opposition and his own party.

In series 4, the government and opposition have switched places following an election during which JB failed to gain a majority and is therefore in coalition government with a smaller third party. Peter Mannion has been made the Secretary of State for Social Affairs and Citizenship but has to contend with Fergus Williams, his junior partner in the coalition. Meanwhile, following Tom Davis's defeat and resignation, Nicola Murray had been elected by her party, apparently on a technicality over Dan Miller, her opponent, as leader of the opposition, although she resigns at the end of episode four and is replaced by her deputy, Miller. A running thread throughout the series is an ongoing "Leveson-style public inquiry" which takes place in episode six. While the first four episodes each focuses solely on one party (episodes one and three focusing on the Coalition, and episode two and four focusing on the Opposition), each episode thereafter cuts between the parties. The final three episodes of series four show both parties trying to cover their tracks regarding a public health care bill which has led to the public eviction and consequent suicide of Douglas Tickel, a nurse with a history of mental illness. All three main parties have some level of responsibility and have participated in the illegal leaking of documents, in particular Tickel's medical records, which is the reason for the Goolding Inquiry being launched.

Most episodes focus on the department's incumbent minister and a core cast of advisers and civil servants, under the watchful eye of Number 10's enforcer, Malcolm Tucker. Over its run, the series has developed a large cast of additional characters, who form the government, opposition, as well as members of the media.The first run of three episodes screened on BBC Four from 19 May 2005. A further three episodes were transmitted 20 October – 3 November 2005. The six episodes were repeated on BBC Two in early 2006, and later on BBC America together as a single series. The subsequent DVD release of all six episodes describes the episodes as "The Complete First Series".

An hour-long Christmas special, "The Rise of the Nutters", aired in January 2007 with a further ten episodes planned for later on in the year. Chris Langham did not reprise his role as Hugh Abbot, due to arrest and later conviction on charges of possession of child pornography, ruling him out of any further roles. To fill this void, Iannucci introduced new characters into the series forming the opposition.

Another one-off hour-long episode "Spinners and Losers" aired on 3 July 2007. It was followed by a 15-minute extra episode through BBC Red Button, following the same story from the opposition's point of view.

For series 3, transmission switched to BBC Two, with subsequent repeats on BBC Four. The series ran for eight episodes from 24 October 2009 to 12 December 2009. As a Red Button extra, each episode had an accompanying 10-minute documentary titled "Out of The Thick of It" broadcast immediately afterwards and on the BBC Comedy website, which featured cut scenes, specially written scenes and, later, discussion of the programme by the series' writers, makers and with figures involved in British politics.

Internationally, series 1 and 2 aired back-to-back in Australia on ABC1 each Friday at 9:40 pm from 21 November 2008 and has since been repeated on ABC2 and UKTV. Later, the two-hour-long specials along with series 3 premiered consecutively on the lower-rated ABC2 channel from 7 July 2011 each Thursday at 10:15 pm and again repeated, this time on ABC1 and UKTV.

A fourth series was commissioned in March 2010. Work began on the scripts in March 2011, filming began in March 2012 and airing started on BBC Two on 8 September 2012. The fourth series is co-produced by Hulu. Iannucci stated that the coalition government, in particular the role of the Liberal Democrats, would remain the target of the next series. In an interview with "The Guardian", he stated his idea was for Peter Mannion to have become a minister "but there will be someone from the other party in the coalition in his office, so a lot of the comedy will come from that tension between duplicated ministers." Press for the fourth series partially focused on the applicability of the show to real life, with Will Smith commenting that the use of the word "omnishambles", coined in the third series, becoming a political meme in the months before transmission being a "baffling" example of life imitating art.

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The series has been the recipient of a number of awards, particularly from BAFTA. Series 1 won both "Best Situation Comedy" and Chris Langham won "Best Comedy Performance – male" at the 2006 BAFTA Television Awards, with Peter Capaldi being nominated for the same award in 2006 and 2008. Capaldi won the BAFTA at the 2010 awards, with Rebecca Front winning "Best Comedy Performance – female". The series was also declared the "Best Situation Comedy".

The series also won Best Situation Comedy from the Royal Television Society in 2006 and 2010, and won Broadcasting Press Guild Awards in 2006 and 2010 for best sitcom and writing team.

In May 2008, the BBC issued a press release stating that filming had commenced on a feature-length adaptation named "In the Loop" starring Tom Hollander, James Gandolfini, Chris Addison, Peter Capaldi, Gina McKee and Steve Coogan. The film followed the plight of the International Development minister as an inadvertent comment in an interview leads to him being used as a puppet by the president of the United States and the prime minister who are looking to launch a war in the Middle East. The film follows the officials and advisers in their behind-the-scenes efforts either to promote the war or prevent it.

Although many of the TV series cast returned, the only actual returning characters are Malcolm Tucker, Jamie McDonald and Sam Cassidy, with series regulars Chris Addison, James Smith, Joanna Scanlan, Alex MacQueen, Olivia Poulet, Eve Matheson and Will Smith playing new characters altogether. The film premiered in the US at the 2009 Sundance Film Festival and in the UK at the 2009 Glasgow Film Festival. It was released on 17 April 2009 in the United Kingdom. "In The Loop" was nominated for an Academy Award for Best Adapted Screenplay in 2010. Several cast members later played similar roles in "Veep".

On 27 October 2006, it was announced that "The Thick of It" would be adapted for American television, focusing on the daily lives of a low-level member of the United States Congress and his staff. "Arrested Development" creator Mitch Hurwitz would be the executive producer, along with Iannucci and Richard Day. The pilot was directed by Christopher Guest, and produced by Sony Pictures and BBC Worldwide. The cast included John Michael Higgins, Oliver Platt, Michael McKean, Alex Borstein, and Wayne Wilderson.

ABC did not pick up the show for its 2007 Autumn schedule. Iannucci distanced himself from the pilot, saying: "It was terrible... they took the idea and chucked out all the style. It was all conventionally shot and there was no improvisation or swearing. It didn't get picked up, thank God." Other networks including HBO, Showtime, and NBC expressed interest in the show, and in April 2009, Iannucci re-entered talks with HBO over the possibility of an American adaptation.

Although it is not a direct spin-off, "Veep" shares a similar tone and style with "The Thick of It". In November 2010 it was announced that HBO had ordered a pilot for a new series called "Veep", to be written, directed and produced by Iannucci. The pilot stars Julia Louis-Dreyfus in the leading role as vice president of the U.S. and also includes several of the American cast members who played similar characters in "In the Loop", most notably series co-star Anna Chlumsky. The series began airing in April 2012. "Veep" began showing in the UK on Sky Atlantic beginning in June 2012.
Justin Edwards and Rebecca Gethings appear in the "Veep" episode "Special Relationship" as different characters.

On 2 April 2007, a UK DVD of the first six episodes was released as "The Complete First Series". It also included audio commentary, deleted scenes, and photo galleries. The two specials were released on a second UK DVD in April 2009. The third series was released on UK DVD in April 2010, followed by a "complete series" box set (now outdated). Although the third series was filmed and broadcast on the BBC in high definition video there has been no release to date on Blu-ray disc. A North American "Series One to Three" DVD box set was briefly scheduled for release in late 2012, but the release was delayed until Aug. 6, 2013, in order to allow all four seasons (plus specials) to be included in what was now a "Complete Series" release. The release date was announced by BBC Worldwide early in 2013, but coincidentally ended up occurring only two days after Peter Capaldi was announced as the new star of "Doctor Who". (Even more coincidental, a cast commentary included as part of a photo gallery featurette for the episode "Rise of the Nutters" included in the DVD set, recorded several years earlier, has several cast members jokingly deciding to start a rumour that Capaldi is to be the next Doctor.)

"The Thick of It: The Scripts", a book containing the scripts from the first two series and the 2007 specials, was published on 1 September 2007.

A tie-in book, "The Thick Of It: The Missing DoSAC Files", was published on 4 November 2010.
An iPhone app – based on the "DoSAC Files" book and named 'Malcolm Tucker: The Missing Phone' – was released in 2010, and was nominated for a New Media award at the 2011 Television BAFTAs.

In the run-up to the 2010 general election, the column 'Malcolm Tucker's election briefing' appeared weekly in "The Guardian", written by Jesse Armstrong.

A one-off column written by Ian Martin in the character of Stewart Pearson – 'Stewart Pearson's Media Notebook' – appeared in "The Guardian" in November 2010.

A column, purportedly an exchange of e-mails between Malcolm Tucker and another Iannucci character, Alan Partridge, on the topic of Britain's exit from the European Union was published in The Big Issue in October 2017 in print and online.
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