A movie that understands the mechanism of microwave oven "How a Microwave Oven Works"

A microwave oven, which is one of the household appliances indispensable for daily life. I talk about the mechanism of various machines on YouTube about how such a microwave oven works in what wayengineerguyIt explains in an easy-to-understand manner.

How a Microwave Oven Works - YouTube


"Microwave ovens are a wonderful achievement in the engineering field," said Bill Hamack, YouTuber, who will explain the mechanism of the microwave oven this time.


"Microwave ovens are made up of three components"


"First of all, this vacuum tube, thisMagnetronIt is a type of vacuum tube called so, which generates energy to heat food. "


"The second one is a hole in the cabinet where the electromagnetic waves come throughWaveguideIt has a role to bring the electromagnetic waves generated by the magnetron connected to the other opening into the cabinet at one opening of the cabin. "


"The third one is a room for hitting food only, not putting out energy outside the storehouse."


"The energy emitted by the magnetron isMicrowaveIt is an electromagnetic wave called microwave, which uses this electromagnetic wave to warm food. "


"In addition to the microwave oven, many heating cookers exist,Heat transferThe mechanism itself does not change. At the molecular level "heat = molecular motion" and if you want to raise the temperature you need to move the molecule. "


"When putting potatoes in an oven or a kettle and warm it ... ...."


"When heated, the inner wall radiates heat and warms the potato from the outside, which tends to increase the temperature outside of the potatoes and lower the temperature in the central part"


"However, when warming with microwaves like a microwave oven, the temperature tends to rise from the central part of the potato."


"Why does it warm from the center?"


"It is a water molecule (H₂O). Water is a compound of hydrogen and oxygen, composed of two hydrogen atoms and one oxygen atom ... "


"Since the hydrogen atom side is charged to the positive (+) pole and the oxygen atom side is charged to the negative (-) pole,Dipole momentIt occurs from the hydrogen atom side to the oxygen atom. "


"And, to apply kinetic energy to these molecules, we will apply microwaves emitted from the magnetron.waveIselectric fieldandmagnetic fieldI have ... .... "


"There is a characteristic that the direction of the electric field and the magnetic field changes quickly.In the case of this microwave oven, the direction of the electric field and the magnetic field changes by 2.45 billion times per second"


"At this time, since water molecules try to line up according to the direction of the electric field, they begin to vibrate in accordance with the movement of the waves, and the water molecules rub against each other, causing molecular friction and generating heat Warming with the heat of molecular friction is the mechanism of the microwave.When heating the potato with the microwave, the reason for warming from the center is that the water molecules contained in the central part of the potato are micro It can be thought that it responded to waves. "



"Next, with cheese, the energy released from the magnetronwavelengthLet's examine. "


After detaching the microwave oven turntable, Mr. Hamac set up a columnar pillar. After that, Mr. Hamac puts a steel plate spreading cheese on the pillar and heats it with a microwave oven.


Mr. Hamac took out the heated cheese and look inside ... ...


You can see that the part surrounded by the red frame is divided into the "(heated) cheese melted places" and the yellow green frame surrounded "(not heated) cheese is not melted".


"This shows that waves are present in the cabinet, this waveStanding waveIt also shows that it creates hot and cold places in the cabinet. "


"In the place where the peak parts of the mountains and valleys of the blue arrow are the hottest ... ...."


"The red dot will not change as the waves move, so it will be a place that will not be heated."


"When you check the spacing of molten cheese, it is 2.5 inches (about 6.4 cm) ... ...."


"It can be seen that the length of half the wavelength of the microwave flowing in the cabinet is about 6.4 cm"


"When we know the length of the wavelength it is possible to find the frequency.The frequency can be obtained by dividing the speed of light by the wavelength and it becomes 2.34 GHz when calculated .. Since the frequency of the actual microwave oven is 2.45 GHz , You can see that it is required with high precision "


"The fact that the most important thing for microwave ovens is that we have created a magnetron capable of emitting high power electromagnetic waves"


"Now, I took out the magnetron part of this microwave oven, but this device is an innovative device.The actual magnetron is smaller, most of the parts visible here are for coolingfinIt is a device for dissipating heat when the magnetron operates. "


"And you can see that a vacuum tube is inside the cooling fin"


"This is the magnetron taken out from the cooling fin, with the upper and lower magnets ..."


"It consists of vacuum tubes"


"There is a copper anode on the outside of the vacuum tube and a cathode filament at the center ..."


"When we apply voltage, we emit electrons from the central filament toward the outer anode."


"The electrons emitted from the central cathode to the anode, due to the magnets attached above and below the vacuum tube,Lorentz forceI will come back to the filament. "


"By successfully adjusting this magnetic force it is possible to operate as a magnetron that can emit microwaves by setting electrons emitted from filaments to return to the cathode while circling round the corners of the anode cylinder "


Finally, Mr. Hamac concludes the movie, "I can not hide surprises as I can realize sophisticated and low-cost sophisticated mechanisms like this"