term paper on microwave oven by noor & dalilur_ict_3rd batch_1st semester_2011

MICRO WAVE OVEN

AUTHER’S NAMES :Noor mohammed MD.Dulilur Rahman

Id No:1109009 Id No:1109041

Course Leder’s Name:

Khondokar Fida Hasan, Lecturer of (ICT)

Comilla University

Department of

Information and Communication Technology(ICT)

Page no:1 Micro waveoven

Comilla University

Department of

Information and Communication Technology(ICT)

The Micro Wave oven

Khondokar Fida Hasan

Email:[email protected]

Noor mohammed MD.Dulilur Rahman

Id No:1109009 Id No:1109041

Email:[email protected]

Submission of date: 25-04-2012


Table of contents

1.Introduction…………………………………………05

2.History of microwave oven…………………………06

Earth oven………………………………………………………………………………………………………………….07

Ceramic oven …………………………………………………07

Gas oven………………………………………………………07

Microwave oven…………………………………………………………………………………………………..08

3.Changes over times……………………………08

A toasted oven…………………………………………………………..08

Panasonic micro wave& grill oven.......................................................................08


http://en.wikipedia.org/wiki/Earth_oven


4.Cooking…………………………………............09

Interior of a modern oven………………………….09

5. Industrial, scientific, and artisanal use………10

6.What are Microwaves……………………………..12

7.Electromagnetic Spectrum…………………………13

8.How the Oven Works………………………………14

Magnetron………………………………………………………………18

How Foods Get Cooked………………………………………………….20

Health Hazards………………………………………………………….21

8.Conclusion…………………………………………..21

9.Bibliography………………………………….........22


10.Appendix

Introduction When people think of microwave ovens, they think about the fact that they are everywhere. They think about the fact that most of the things that they cook and heat will come out of the microwave and use the technology. Microwave ovens are one of the most popular ways to cook and heat food. While there are multiple types of microwaves, and different ways to use a microwave oven, all of them do nearly the same thing.


While microwave ovens will all do the same thing, there are different types of microwaves to choose from. Some of the microwaves simply look different, as they have been given a sharper and cleaner design to fit in a more upscale type of kitchen, while others will tweak how the microwave works, especially with how fast it can work. These tweaks and changes aim to help those who are actually purchasing the microwave.

The over-the range microwave was one of the most important changes that the microwave has ever seen. Putting the microwave over the range actually helped to bring the microwave into the kitchen in a way that did not take up counter or shelf space. This was important, as it solidified the microwave's stance as a major kitchen appliance, despite its size.

One of the other major changes to the small appliances is the strength of the microwave. While certain microwaves will have different strengths of their own, some microwaves will simply have higher strengths than others. This turns some microwaves into major appliances, as some microwaves can heat things in a faster and more efficient way.

There are a few important things that you should take into consideration before you actually purchase a new microwave oven. While the microwave is partially about the look (and the overall feel of the entire kitchen itself), there are many more aspects that many people will not even consider, but could actually affect how happy you are with your microwave purchase.

History of micro oven

Ancient Greek portable oven, 17th century BCE

The earliest ovens were found in Central Europe, and dated to 29,000 BC, it was used as roasting and boiling pits located within yurt structures.

They were used to cook mammoth.[2] In Ukraine from 20,000


BC they used pits with hot coals covered in ashes.

The food was Wrapped in

leaves and set on top,

then covered with earth.[3]

In camps found in Mezhirich,

each mammoth bone house had a hearth used for heating and cooking.[4]

Ovens have been used since prehistoric times by cultures who lived in the Indus Valley and pre-dynastic Egypt.[5][6] Settlements across the Indus Valley had an oven within each mud-brick house by 3200 BC.[5][7][5] The obvious explanation for the popular use of the oven in the homes would most likely involve its use for cooking food. However, baked brick sewers were also found at the Indus Valley civilization, which shows that they used the oven for masonry as well.[5] Other ancient cultures that had use for the oven were pre-dynastic civilizations in Egypt. An early form of blacktopware was produced there which required a kiln. This is another hint showing how ovens were used from about 5000–4000 BC.[6]

Culinary historians credit the Greeks for developing bread baking into an art. Front-loaded bread ovens were developed in ancient Greece. The Greeks created a wide variety of doughs, loaf shapes, and styles of serving bread with other foods. Baking developed as a trade and profession as bread increasingly was prepared outside of the family home by specially trained workers to be sold to the public. This is one of the oldest forms of professional food processing.

Earth oven : An earth oven is a pit dug into the ground and then heated, usually by rocks or smoldering debris. Historically these have been used by many



http://en.wikipedia.org/wiki/File:MuseAcrotiriItem160-6648-1.jpg

cultures for cooking. Cooking times are usually long, and the process is usually cooking by slow roasting the food. It is also important to note that earth ovens are amongst the most common things Archaeologist look for at an anthropological dig, as they are one of the key indicators of human civilization and static society.[8]

Ceramic oven: The ceramic oven is an oven constructed of clay or any other ceramic material and takes different forms depending on the culture. The Indians refer to it as a tandoor, and use it for cooking. They can be dated back as far as 3,000 BC, they have been argued to have their origins in the Indus Valley.[6] Brick ovens are also another ceramic type oven. A culture most notable for the use of brick ovens is Italy and its intimate history with pizza. But its history goes back even further dating to Roman times when the brick oven was used not only for commercial use but household use as well.[9]

Gas oven: One of the first recorded uses of a gas stove and oven referenced a dinner party in 1802 hosted by Zachaus Winzler, where all the food was prepared either on a gas stove or in its oven compartment. In 1834, British inventor James Sharp began to commercially produce gas ovens after installing one in his own house. In 1851, the Bower's Registered Gas Stove was displayed at the Great Exhibition. This stove would set the standard and basis for the modern gas oven. Notable improvements to the gas stove since include the addition of the thermostat which assisted in temperature regulation; also an enamel coating was added to the production of gas stoves and ovens in order to help with easier cleaning.[10]

Masonry oven: Masonry ovens consist of a baking chamber made of fireproof brick, concrete, stone, or clay. Though traditionally wood-fired, coal-fired ovens were common in the 19th century, modern masonry ovens are often fired with natural gas or even electricity. Modern masonry ovens are closely associated with artisanal bread and pizza, but in the past they were also used for any cooking task that required baking.

Microwave oven: An oven that uses micro radiation waves as a source of heat in order to cook food as opposed to a fire source. Conceptualized in 1946, Dr. Perry Spencer allegedly discovered the heating properties of microwaves while studying the magnetron. By 1947, the first commercial microwave was in use in Boston, Mass.[11]

Changes over time A toaster oven


A Panasonic microwave & grill oven

During the Middle Ages, instead of earth and ceramic ovens, Europeans used fireplaces in conjunction with large cauldrons. These were similar to the Dutch oven. Following the Middle-Ages, ovens underwent many changes over time from wood, iron, coal, gas, and even electric. Each design had its own motivation and purpose. The wood burning stoves saw improvement through the addition of fire chambers that allowed better containment and release of smoke. Another recognizable oven would be the cast-iron stove. These were first used around the early 1700s when they themselves underwent several variations including the Stewart Oberlin iron stove that was smaller and had its own chimney.[12]

In the early part of the 19th century, coal ovens were developed. Its shape was cylindrical and was made of heavy cast-iron. The gas oven saw its first use as early as the beginning of the 19th century as well. Gas stoves became very common household ovens once gas lines were available to most houses and neighborhoods. James Sharp patented one of the first gas stoves in 1826. Other various improvements to the gas stove included the AGA cooker invented in 1922 by

Gustaf Dalen. The first electric ovens were invented in the very late 19th century, however, like many electrical inventions destined for commercial use, mass ownership of electrical ovens could not be a reality until better and more efficient use of electricity was available.[12]

More recently, ovens have become slightly more high-tech in terms of cooking strategy. The microwave as a cooking tool was discovered by Percy Spencer in 1946, and with the help from engineers, the microwave oven was patented.[12] The microwave oven uses microwave radiation to excite the molecules in food causing friction, thus producing heat.[13]

Cooking

Interior of a modern oven

In cooking, the conventional oven is a kitchen appliance used for roasting and heating. Food normally cooked in this manner include meat, casseroles and baked


goods such as bread, cake and other desserts. In modern times, the oven is used to cook and heat food in many households across the globe.

Modern ovens are fueled by gas or electricity. When an oven is contained in a complete stove, the fuel used for the oven may be the same as or different from the fuel used for the burners on top of the stove.

Ovens usually can use a variety of methods to cook. The most common may be to heat the oven from below. This is commonly used for baking and roasting. The oven may also be able to heat from the top to provide broiling. In order to provide faster, more-even cooking, convection ovens use a small fan to blow hot air around the cooking chamber. An oven may also provide an integrated rotisserie.

Ovens also vary in the way that they are controlled. The simplest ovens (for example, the AGA cooker) may not have any controls at all; the ovens simply run continuously at various temperatures. More conventional ovens have a simple thermostat which turns the oven on and off and selects the temperature at which it will operate. Set to the highest setting, this may also enable the broiler element. A timer may allow the oven to be turned on and off automatically at pre-set times. More sophisticated ovens may have complex, computer-based controls allowing a wide variety of operating modes and special features including the use of a temperature probe to automatically shut the oven off when the food is completely cooked to the desired degree.

Some ovens provide various aids to cleaning. Continuous cleaning ovens have the oven chamber coated with a catalytic surface that helps break down (oxidize) food splatters and spills over time. Self-cleaning ovens use pyrolytic decomposition (extreme heat) to oxidize dirt. Steam ovens may provide a wet-soak cycle to loosen dirt, allowing easier manual removal. In the absence of any special methods, chemical oven cleaners are sometimes used or just old-fashioned scrubbing.

Industrial, scientific, and artisanal use

Example of an industrial bakery oven Outside the culinary world, ovens are used for a number of purposes.


A furnace can be used either to provide heat to a building or used to melt substances such as glass or metal for further processing.

A blast furnace is a particular type of furnace generally associated with metal smelting

(particularly steel manufacture) using refined coke or similar hot-burning substance as a fuel, with air pumped in under pressure to increase the temperature of the fire.

A kiln is a high-temperature oven used in wood drying, ceramics and cement manufacturing to convert mineral feedstock (in the form of clay or calcium or aluminum rocks) into a glassier, more solid form. In the case of ceramic kilns, a shaped clay object is the final result, while cement kilns produce a substance called clinker that is crushed to make the final cement product. (Certain types of drying ovens used in food manufacture, especially those used in malting, are also referred to as kilns.)

An autoclave is an oven-like device with features similar to a pressure cooker that allows the heating of aqueous solutions to higher temperatures than water's boiling point in order to sterilize the contents of the autoclave.

Industrial ovens are similar to their culinary equivalents and are used for a number of different applications that do not require the high temperatures of a kiln or furnace.


http://en.wikipedia.org/wiki/File:Pec_na_chleba.JPG

What are Microwaves?

Microwaves are a form of electromagnetic energy, like light waves or radio waves

Microwaves are used extensively in communications

such as to relay long-distance telephone signals, television programs and computer information across the earth or to a satellite in space.


Good for transmitting information because it can penetrate haze, light rain and snow, clouds, and smoke.

Also used in radars and in detecting speeding cars.

Microwave has become most familiar as the energy source for cooking

food.

Electromagnetic Spectrum

Electromagnetic radiation exists in a range of frequencies called the electromagnetic spectrum.

Each frequency has a specific wavelength and as the frequency decreases, the actual length of the wave gets longer.

Table 1: Frequency and Wavelength Range of Each Radiation Type in the Electromagnetic Spectrum.

Radiation Type Frequency Range (Hz) Wavelength Range

Gamma rays above 3 x 1019 < 10-12 m

X-rays 3 x 1017 - 3 x 1019 1 nm - 1 pm


Ultraviolet Radiation 7.5 x 1014 - 3 x 1017 400 nm - 1 nm

Visible Spectrum3.8 x 1014 - 7.5 x

1014750 nm - 380 nm

Infrared Radiation 1011 - 3.8 x 1014 25 um - 2.5 um

Microwaves 108 - 1012 1 mm - 25 um

Radio waves 104 - 108 >1 mm

How the Oven Works

Electricity from the wall outlet travels through the power cord and enters the microwave oven through a series of fuse and safety protection circuits

These circuits include various fuses and thermal protectors that are designed to deactivate the oven in the event of an electrical short or if an overheating condition occurs

When the oven door is closed, an electrical path is also established through a series of safety interlock switches


• The magnetron converts the high voltage in to the microwave frequency for cooking

• The microwave energy is transmitted into a waveguide

• The waveguide feeds the energy to the stirrer blade and into the cooking area

• When the door is opened, or the timer reaches zero, the microwave energy stops.


• Sensing that all systems are set to go, the signal activates triac, producing a voltage path to the high-voltage transformer.

The high-voltage transformer along with a special diode and capacitor arrangement increases the typical household voltage from ~115 volts to ~3000 volt.


Megnatron


Electrons from a hot filament would travel radially to the outside ring if it were not for the magnetic field. The magnetic force deflects them as shown and they tend to sweep around the circle. In doing so, they “pump” the natural frequency of the cavities. The currents around the resonant cavities cause them to radiate electromagnetic energy at that resonant frequency.


How Foods Get Cooked

The microwaves that penetrate the food have an electric field that oscillates 2.45 billion times a second, a frequency that is well absorbed by polar liquid molecules such as water, sugars, fats and other food molecules.

Water interacts with the microwave:

flipping its orientation back and forth very rapidly

bumping into one another and producing heat, cooking the food.

Glass, paper, ceramic, or plastic containers are used in microwave cooking because the microwaves pass through them

Metal reflects microwaves

Unsafe to have metal pans/aluminum foil in oven, may damage oven


Health Hazards

It is known that microwave radiation can heat body tissue the same way it heats food.

Exposure to high levels of microwaves can cause a painful burn

Ex. the lens of the eye ~ exposure to high levels of microwaves can cause cataracts.

Microwave oven used low level of microwaves, within the region of non-ionizing radiation

Still uncertain in the effects of humans from long term exposure to low level of microwaves

Still experimenting

Best to stay a way (an arm’s length) in reducing exposure to microwaves

Conclusion

In the last moment ,we have told that the micro wave oven is one of the greatest scientific invention .It has become so easier in our daily life saving so much time in cooking and it can make so much delicious food which is very tasteful and healthy.At present,we use micro oven in industrial works that is very helpful for making food. In the next generation,we may get the latest technology of micro wave oven which will be able to do anything without electricity.


Bibliography

1. Oven. Merriam-webster.com. Retrieved on 2011-11-23.2. Jennifer Viegas Mammoths roasted in prehistoric barbecue pit.

MSNBC. updated 6/3/2009. Retrieved on 2011-11-23.3. ̂ Peter James; Nick Thorpe; I. J. Thorpe (31 October 1995).

Ancient inventions. Random House Digital, Inc.. pp. 302–. ISBN 978-0-345-40102-1. Retrieved 23 November 2011.

4. ̂ Mezhirich. Donsmaps.com. Retrieved on 2011-11-23.5. ^ a b c d History Of The Indus Civilization. Historyworld.net.

Retrieved on 2011-11-23.6. ^ a b c Hierkonpolis Online. "Pottery Kilns."7. ̂ Dales, George (1974), "Excavations at Balakot, Pakistan, 1973",

Journal of Field Archaeology (Boston University) 1 (1–2): 3–22 [10], doi:10.2307/529703, JSTOR 529703

8. ̂ Dering, Phil (1999). "Earth-Oven Plant Processing in Archaic Period Economies: An Example from a Semi-Arid Savannah in South Central North America". American Antiquity 64: 659–674. JSTOR 2694211.

9. ̂ Forno Bravo. "The History of Brick Ovens."10. ̂ The Gas Museum Leicester. "Gas Cooking."11. ̂ Microtech. “Who Invented Microwaves.”12. ^ a b c Bellis, Mary. "History of the Oven from Cast Iron to

Electric."13. ̂ Gallawa, Carlton J. "How do Microwaves Cook."


term paper on microwave oven by noor & dalilur_ict_3rd batch_1st semester_2011

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