presentation on micro wave oven

8/14/2019 Presentation on Micro Wave Oven

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Micro Wave

Oven


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Introduction

A microwave oven, or a microwave, is akitchen appliance that cooks or heats food by

dielectric heating. This is accomplished by using

microwave radiation to heat water andother polarized molecules within the food. This

excitation is fairly uniform, leading to

food being adequately heated throughout(except in thick objects), a feature not seen in

any other heating technique.


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Different Models of Microwaves


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History of Micro Wave Oven

Microwaves was discovered accidentally inthe 1940s by a self-taught engineer NamedPercy Spencer.

He was working on an active radar set whenhe noticed that a peanut chocolate bar hehad in his pocket started to melt. The radar

had melted his chocolate bar withmicrowaves.


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History

In 1947, the company built the Radarange,the first microwave oven in the world. It wasalmost 6 feet (1.8 m) tall, weighed 750

pounds (340 kg) and cost about US$5,000each. It consumed 3 kilowatts,

An early commercial model introduced in

1954 consumed 1600 watts and sold forUS$2,000 to US$3,000.


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Inventor the microwave oven

Dr. Percy Spencer


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Working of Microwave Oven

A microwave oven works by passing non-ionizing microwave radiation, usually at afrequency of 2.45 gigahertz (GHz) (a

wavelength of 12.24 cm (4.82 in)), throughthe food.

Microwave radiation is between common

radio and infrared frequencies.


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Working

Water, fat, and other substances in the foodabsorb energy from the microwaves in a processcalled dielectric heating. Many molecules (such asthose of water) are electric dipoles, meaning that

they have a positive charge at one end and anegative charge at the other, and therefore rotateas they try to align themselves with the alternatingelectric field of the microwaves. This molecular

movement represents heat which is then dispersedas the rotating molecules hit other molecules andput them into motion.


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Different Parts of Microwave Oven

A microwave oven consists of:

1- A high voltage transformer, which passes energyto the magnetron

2- A cavity magnetron, which converts high-voltageelectric energy to microwave radiation .

3- A magnetron control circuit (usually with a

microcontroller)3- A waveguide

4- A cooking chamber.


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Different Parts of Microwave Oven


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High voltage transformer,


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Magnetron Cavity Structure


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Types and Sizes of Micro wave

Consumer microwaves typically come intwo types

1- Compact Type Micro Wave.

Compact Type Micro Wave comes in three Sizes

a- Compact size Micro wave

b- Medium size Micro wavec- Largesize Micro wave

2- Built-in Type Micro Wave.


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ADVANTAGES

Cooking time is short

Destruction of nutrients is less

No physical change of foodsMelting process is easy

Sterilization effect exists

There is no flame, then treatment is easy.


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DISADVANTAGES

Constraint with metal container

Heat force control is difficult

Water evaporationClosed container is dangerous because it

could be burst

Surface toasting is impossible


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CONCLUSION

Microwave oven is amazing householdappliance to heat up foods by usingmicrowaves. This Microwave has frequency

equals the resonance frequency of water.Therefore foods could be heat up byoscillation of water molecules.


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THE END

presentation on micro wave oven

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