How a microw wave oven work ?

Question

How a microw wave oven work ?

Answer 1

How did you finish school if you can't even complete a proper sentence?

Answer 2

A microwave oven consists of:

a high voltage transformer, which passes energy to the magnetron

a cavity magnetron,

a magnetron control circuit (usually with a microcontroller),

a waveguide, and

a cooking chamber

A microwave oven works by passing non-ionizing microwave radiation, usually at a frequency of 2.45 GHz (a wavelength of 12.24 cm), through the food. Microwave radiation is between common radio and infrared frequencies. Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating. Many molecules (such as those of water) are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. This molecular movement creates heat as the rotating molecules hit other molecules and put them into motion. Microwave heating is most efficient on liquid water[citation needed], and much less so on fats and sugars (which have less molecular dipole moment), and frozen water (where the molecules are not free to rotate). Microwave heating is sometimes explained as a resonance of water molecules, but this is incorrect: such resonance only occurs in water vapor at much higher frequencies, at about 20 gigahertz[5]. Moreover, large industrial/commercial microwave ovens operating at the common large industrial-oven microwave heating frequency of 915 MHz (0.915 GHz), also heat water and food perfectly well. [6] The frequencies used in microwave ovens were chosen based on two constraints. The first is that they should be in one of the ISM bands set aside for non-communication purposes. 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. 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.

A common misconception is that microwave ovens cook food from the "inside out". In reality, microwaves are absorbed in the outer layers of food in a manner somewhat similar to heat from other methods. The misconception arises because microwaves penetrate dry non-conductive substances at the surfaces of many common foods, and thus often induce initial heat more deeply than other methods. Depending on water content, the depth of initial heat deposition may be several centimetres or more with microwave ovens, in contrast to broiling (infrared) or convection heating, 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 better.

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

The cooking chamber itself is a Faraday cage enclosure which prevents the microwaves from escaping into the environment. The oven door is usually a glass panel for easy viewing, but has a layer of conductive mesh to maintain the shielding. Because the size of the perforations in the mesh is much less than the wavelength of 12 cm, most of the microwave radiation cannot pass through the door, while visible light (with a much shorter wavelength) can. With wireless computer networks gaining in popularity, microwave interference has become a concern near wireless networks. Microwave ovens are capable of disrupting wireless network transmissions because the ovens generate radio waves of about 2.45 GHz in the 802.11b/g frequency band, some of them escaping the enclosure despite the presence of the mesh.

Answer 3

Hi

Actually microwave oven works with the help of water molecules present in the food items. tomatoes were cooked quicker than that of a carrot.

Actually one end of microwave oven will have positive end and other will have negative end.  We know that you all molecules will have both positive and negative points.

The oven starts by activating the negative and positive ends rapidly resulting in the breaking up of molecules resulting in evolution of heat energy which help to cook food.

Sorry 4 the lengthy answer

Bye...

Answer 4

A microwave oven uses electricity to send micro-waves down on the item in the oven. A cellphone does the same thing except less microwaves. Use your cellphone rarely, and stand far behind a microwave oven, or you could get brain damage. I'm only suggesting.

Answer 5

Open door.

Put in meal.

Set timer.

Press button.

Answer 6

ITB WORKS ON THE PRINCIPLES OF CONVENTIONS.

Answer 7

Dear Dr. Spencer,

You should probably learn to spell first.  The "microwave" questions will come later.  

Answer 8

hey y dont ya step inside it & check out!!!!!

Answer 9

Microwaves work by giving out heat,then the substance in the oven absorbs the heat by releasing water an then becomes hot.

Answer 10

they have a thing called MAGNETRON. which gives out electromagnetic waves with wavelengths r, or frequencies.

which cooks your food.

Answer 11

howstuffworks.com

Answer 12

The heating in a microwave oven is dielectric (or "dipole") heating.  See http://en.wikipedia.org/wiki/Microwave_o... for a pretty good explanation (and a good history of the device).

Answer 13

Microwave ovens use various combinations of electrical circuits and mechanical devices to produce and control an output of  microwave energy  for heating and cooking. Generally speaking the systems of a microwave oven can be divided into two fundamental sections, the   control section   and the   high-voltage section   .

The control section consists of a timer (electronic or electromechanical), a system to control or govern the power output, and various interlock and protection devices. The components in the high-voltage section serve to step up the house voltage to high voltage. The high voltage is then converted microwave energy.

Basically, here is how it 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

If all systems are normal, the electricity passes through to the interlock and timer circuits. When then oven door is closed, an electrical path is also established through a series of safety interlock switches . Setting the oven timer and starting a cook operation extends this voltage path to the control circuits .

Generally, the control system includes either an electromechanical relay or an electronic switch called a triac. Sensing that all systems are "go," the control circuit generates a signal that causes the relay or triac to activate, thereby producing a voltage path to the high-voltage transformer . By adjusting the on-off ratio of this activation signal, the control system can govern the application of voltage to the high-voltage transformer, thereby controlling the on-off ratio of the magnetron tube and therefore the output power of the microwave oven. Some models use a fast-acting power-control relay in the high-voltage circuit to control the output power.

In the high-voltage section , the high-voltage transformer along with a special diode and capacitor arrangement serve to increase the typical household voltage, of about 115 volts, to the shockingly high amount of approximately 3000 volts! While this powerful voltage would be quite unhealthy -- even deadly -- for humans, it is just what the magnetron tube needs to do its job -- that is, to dynamically convert the high voltage in to undulating waves of electromagnetic cooking energy.

The microwave energy is transmitted into a metal channel called a waveguide , which feeds the energy into the cooking area where it encounters the slowly revolving metal blades of the stirrer blade . Some models use a type of rotating antenna while others rotate the food through the waves of energy on a revolving carousel. In any case, the effect is to evenly disperse the microwave energy throughout all areas of the cooking compartment. Some waves go directly toward the food, others bounce off the metal walls and flooring; and, thanks to special metal screen, microwaves also reflect off the door. So, the microwave energy reaches all surfaces of the food from every direction.

All microwave energy remains inside the cooking cavity. When the door is opened, or the timer reaches zero, the microwave energy stops--just as turning off a light switch stops the glow of the lamp

i hope it helps you to understand it now!

Answer 14

A microwave oven uses high-pitched sound waves that vibrate at the natural frequency of a water molecule. This causes all the water in a substance to vibrate, increasing their kinetic energy, and the heat of the food.