How a Microwave Oven Works

Bill details how a microwave oven heats food. He describes how the microwave vacuum tube, called a magnetron, generates radio frequencies that cause the water in food to rotate back and forth. He shows the standing wave inside the oven, and notes how you can measure the wavelength with melted cheese. He concludes by describing how a magnetron generates radio waves. You can learn more about the microwave oven from the EngineerGuy team's new book Eight Amazing Engineering Stories www.engineerguy.com/elements

[@leerman22]

The wavelength can be determined "with cheese". Best science ever!

[@KheyZeeMenezThatsMeAlright]

Totally agree!

[@Mitche23]

Thanks zoidberg

[@65532one]

with cheese? why not zoidberg?

[@leerman22]

***** WAT?

[@mrbadx19]

leerman22 would be better with bacon :)

[@skinnyfoodie2437]

End of 2022, you will remain one of the best engineers explaining daily stuff to a normie. Love your videos!!

[@engineerguyvideo]

Thank you

[@damnwereinatightspot]

I agree. the candle, the can the bird, all great. id heard in another doc about the father of the microwave and how it was discovered on accident with a chocolate bar in his shirt pocket... i seem to remember someone asking him if the turntable on or off made a difference, he'd said it didnt from what I recall, any imput?

[@damnwereinatightspot]

@@engineerguyvideo thank you for the videos, hope your well and of course maybe you could do another? :) greetings from AK

[@engineerguyvideo]

I am in the studio at this moment setting up to film more - and should not be responding to you tube comments! - a 4 part series sometime in March.

[@ericeaton2386]

@@engineerguyvideo Exciting! Can't wait to see it :)

[@jalanlamb]

My father, who just passed at 89, worked as a senior electrical engineer at Tappan for over 30 years to perfect the Microwave oven for home use. Our family became guinea pigs as we tested some of the prototypes in our home kitchen. He said making it safe was the hardest & biggest accomplishment of his life. And this is from a guy who co-invented the electronic strobe flash at MIT, helped Jacque Cousteau with underwater lights, and worked on the Hydrogen bomb for the Army, blowing up Enewetak Atoll before he left to work on the Microwave. Anything for science!

[@Discovery_and_Change]

Wow. Incredible and brilliant

[@cbtillery135]

I wish I could have known this man. He sounds like an actual genius.

[@LAK_770]

You basically just described Doc Edgerton, who died in 1990 at age 86. Unless you’re talking about a *different* guy who also happened to invent strobe flash photography at MIT, work with nuclear tests, AND design equipment for Jacques Costeau. Except that if this other guy apparently died at age 89 in ~2019, this means he was an infant/toddler when he co-invented the strobe flash with Edgerton in the early 1930s. That’s really the clincher. Sorry, but either you’ve been hoodwinked with family tall tales, or you’re bafflingly making this up. I’m sure your grandpa was a cool dude and I don’t really doubt he was a scientist who maybe worked on microwaves, but he was not this exact dude you describe.

[@jalanlamb]

Yes, Doc was my Dad's advisor. They ended up good friends. I got to meet him while at OSU, he was giving a lecture on photography. Afterwards I went up to introduce myself. He not only remembered my name, but my mom, and middle brother. He was a brilliant & great lecturer.

[@Xenoz-]

Rest in peace

[@Softail77us]

My first job out of tech school in 1979 was repairing microwave ovens. Back then people were still leery and called my office saying their baby was going to have 3 heads etc. It was also when the mechanical buttons and controls on the front were being replaced with touch panels. All solid state. No moving parts! They went bad constantly but were easy to replace. The big diode inside failed often too but that's about it. Sometimes the wave guide had to be straightened out and or repainted. Litton, Amana, JennAire were big names. Only rich bastards had microwaves back then. Some had browning units so the meat would 'look' cooked. I moved from fixing microwaves to computers now. Nobody had computers back then, the IBM PC wasn't invented yet and Atari? Really? I ignored them although the study of flip flops and microprocessors was very interesting. Sorry for rambling. Thanks for the video! The cheese was a great example!

[@adamh5075]

Softail77us First-hand stories like yours are some of the most valuable KZbin comments.

[@Softail77us]

@@adamh5075 That's cool to hear. Thanks.

[@jeffw1267]

My mother had a late 1970s microwave. It had a heating element so it was a hybrid microwave/electric oven. Apparently women didn't yet trust a standalone microwave.

[@MT-in3tp]

I had never heard the word "leery" before. Learned a whole lot from your comment. Thanks

[@Softail77us]

@@jeffw1267 Some may have been hybrid like you said but a lot of the time the element was there to brown the meat because microwaves don't turn meat brown even though it's cooked. People would think it was uncooked so the heating element made it look cooked. Late 70's eh? I was working on them in 77 right after I graduated tech school before moving towards rf and then digital electronics.

[@DynestiGTI]

And that's why microwaves have turntables to cook the food somewhat evenly instead of leaving hot and cold spots.

[@peters8758]

Instead of a turntable, some models move the energy around while the food stays still. They put rotating reflectors in front of where the microwaves enter the chamber (think of a disco ball bouncing a projector's light around). Both ways work.

[@theafricannetworker8229]

DynestiGTI true! The turntable and autorotating pads help to make sure that food is heated evenly!

[@gylangadi9621]

genius

[@casparvoncampenhausen5249]

Technically you'd then have hot and cold rings, right?

[@jegjeet]

@@casparvoncampenhausen5249 , with cold you mean totally unheated ring or less heated ring? If you mean totally unheated rings then, No. It's 3- dimensional chamber with some cold or less excited spots. If a ring shape portion of food face more these cold spots than other ring portion. So yeah. There is slight chances one ring will be more hot and one slightly less. Not much.

[@Hebbs]

I love that fact I own something called a “Magnatron”

[@Thantaros85]

TRANSFORMER!

[@Moobear30]

@@Thantaros85 More than heats the pie!

[@lesthomasson7220]

David M Took me a second to figure out where you were going with that. That was pretty good. God I’m old

[@jilleswassink7762]

Fun fact: in a lot of languages the entire microwave is called the magnatron (or variants)

[@TVGanesh]

Hahaha ... I have one, too. But there's something more. When I remove the heated food, the bowls/glass plate collide often. So, I have a ... "Magnetron Collider."

[@makeminefreedom]

I can see that the carousel is a very important part of the microwave. When the food rotates through the static field it ensures that every part of the food is heated not just a grid pattern of hot and cold areas. Thanks for making this video.

[@Intrafacial86]

Thanks for actually getting into the nitty gritty of how microwave ovens _actually work_ - that is, how the waves are produced and why they cause molecules to oscillate enough to add heat energy to the food.

[@mysterioso2006]

So in summary, microwaves are decently sized boxes that shake your food so fast that it heats up.

[@elephantgrass631]

Well, shakes the water in your food.

[@notoriousbills]

Magic boxes!

[@pipsantos6278]

No water no heating...sort of.

[@watch10me]

No its not... Wrong summary

[@kreatra7188]

I guess... Yeah. that sounds about right! lol

[@beirirangu]

1:35 "In contrast, the energy from the magnetron penetrates into the food, which means the whole mass of the food can be cooked simultaneously." - a man who's obviously never had a hotpocket

[@double-you5130]

that's why the table rotates inside a microwave. next time double the time and reduce the heating power by 50% and your hotpocket will be heated properly and not burnt in places. 100% power should only be used to heat liquids...

[@cranelord]

You should also put your food on the outside of the tray so one part doesn't stay in a cold spot

[@Adenzel]

@Alien Creation Afaik microwave can penetrate about 2cm into most food, but then the rest of the food relies on convection to heat.

[@billyyfire]

@@double-you5130 " 100% power should only be used to heat liquids..." Now that's some statement!

[@estoylaroca]

If I'm understanding things correctly, he says that the microwave works by heating up the "water" inside the food. So doesn't this mean that more water = faster heat generation. And from this, we can look at the composition of a hotpocket. The outside bread should (at least that's what I believe) contain less water than the sauce/filling inside. Which in conclusion should mean that even though it's heating the whole mass "simultaneously", the composition of the food affects how much heat it would be absorbing. Or in very simple terms: Bread = less water = less heat = longer to get hot. Filling = more water = more heat = faster to get hot. Correct me if any of my reasoning is incorrect.

[@joeenglishtv]

No need for any other explanatory video about 'microwave ovens': this man is just a great teacher!!!!

[@LightFrogs]

I cannot be the only one that is awestruck every time I can heat up my tea in 30 seconds

[@Quicksilver_Cookie]

Measuring wave length of microwave radiation using cheese...Does science ever gets any better than this?

[@MrRahulvekaria]

jethjmadh

[@E-Kat]

MrCorvusC one can eat the equipment!

[@ericklopes4046]

You may use chocolate

[@szabolcsmate5254]

Any cheesier you mean... :D

[@carloko08]

you sugest something better or more simple? you dont know that the more simple is and explanation more brilliant the explainer?

[@garydunken7934]

Cool, using grated cheese to measure wavelength was epic. I'll test in mine.

[@jmatt98]

G Yogaraja were the results delicious 😋 🧀?

[@napoleon_bonaparte2462]

The original method is to use receipt paper, but I can see this being much safer.

[@kopp1948]

Chocolate is better. You can identify the hot spot with greater accuracy.

[@chrismcgoldrick3950]

Using the cheese to show the standing wave pattern was very informative. Now you can see why there are turntables, so as to rotate the food through the different parts of the standing wave and get more uniform heating.

[@joreemmcmillan7145]

Thank you, Bill Hammock, for this clear and concise video about how a microwave oven works. Also, those ‘speed-ups’ look really cool.

[@DanRichter]

lol my parents used to tell me when I was a kid that it was the light bulb that was heating the food. They probably didn't know the real answer either

[@walterkersting1362]

Dan R. Makes you wonder what else they didn’t know...

[@wyattwatterud3099]

walter kersting how to use contraceptives

[@shayanmoosavi9139]

Still better than the people who think microwaves "nuke" the food. I cringe every time I hear it.

[@tkeleth2931]

@@shayanmoosavi9139 It was invented right after the 2nd World War, the whole idea of "nuclear" anything was on the mind of everyone on Earth. It's certainly just slang that was picked up as a result of the era in which it existed.

[@shayanmoosavi9139]

@@tkeleth2931 I know it's a slang but this slang causes misconceptions that the radiation from a microwave is the same as gamma radiation. The microwave radiation is non-ionizing radiation which means it doesn't strip atoms of their electrons and doesn't cause harm to living cells. Ultraviolet, X, and gamma radiation however are ionizing radiation which means that they can strip atoms of their electrons and can cause harm to the living cells. They can even kill cells if the radiation is too much. For example sunburn is caused by the UV from the sun (harming cells) and UV light is used in hospitals to sterilize the surgery tools because it can kill the bacteria and viruses. That's simply not the case for microwaves. They just increase the kinetic energy of the water molecules or in other words heat it up a little. The only way microwave radiation can harm you is if it heats you up too much and that's not easy because water has a very high heat capacity and don't heat up easily.

[@username42]

it is 2019 and still it is best explanation ever made about how a microwave oven works

[@RamalRama]

is still 2019? Yo, I'm in 2020 and there's a pandemic going on in the whole world. You'll be in lockdown for months. Go get some hand sanitizer NOW!

[@ArchangelExile]

@@RamalRama I'm near the end of 2020 and Biden had just won the election.

[@carlodave9]

I thought I sorta understood my microwave -- I did not.

[@georgesracingcar7701]

It is 2021 and it’s… still happening When will it be over

[@username42]

@@georgesracingcar7701 ikr :D

[@TavinTyrone]

To think that somebody had to figure all this out to begin with.

[@RichWoods23]

It wasn't all done in one go with the intent of producing an energy-efficient domestic cooking device. The magnetron was invented over a century ago as part of the general investigation into electromagnetism and the eventual development of radio. The cavity magnetron was invented at the start of WW2 in the search for a means to equip RAF nightfighter aircraft with radar sets. It was only later in the 1960s that someone realised the microwave energy had a heating effect which could be exploited. Entirely separate to that, there's a possibly apocryphal story from the 1970s where radar engineers working on fighter jets (a Soviet Mig-23 in the version I heard) found that their ground tests of the jet's powerful scanning and lock radar sometimes resulted in the lock mode accidentally flash-cooking rabbits a kilometre away...

[@harbirsingh7266]

When they were testing it they noticed the waves had melted a chocolate in someone's pocket. Then they started looking into the technology to heat food.

[@uncannyvalley2350]

A lot of Bothans died to get us this information

[@HarukiYamamoto]

It was from an accident . And the device did not appear on the scene fully formed.

[@KingIsulgard]

@Ethan Ansell Well, when working on a death ray or something, a microwave is a disappointing result.

[@IdiotEarthworm]

Very good explanation. Thanks for making it so simple yet keeping all the technical stuff in.

[@EebstertheGreat]

Microwaves do _not_ penetrate deeply into food. Typically, microwaves penetrate at most a centimeter into the food. While that's more than a convection oven, it's certainly far from "the whole mass of the food [...] cooked simultaneously." Your chart is even more wrong, giving the popular misconception that microwave ovens cook food "from the inside out." The description of the cavity magnetron is wrong too. Every cavity actually acts as a separate resonator, with the parallel sides acting as a capacitor and the circular anode as an inductor. Electrons do not "brush" the anode and return to the cathode, which could not possibly create a current; rather, they travel to the anode in spiraling paths, thus creating brief charge separation on the anode, driving the currents around the cavities. Furthermore, it's not just the water in food that is heated by the microwaves but all dielectric materials. Water is a good absorber due to its high dielectric constant (which is indeed due to its chemical polarity), but many other substances are too. In fact, dry food may heat more quickly than wet food, since water's high heat capacity allows it to absorb more heat (and if it starts boiling, that will also absorb a tremendous amount of heat).

[@Jensaw101]

I can't claim to know how a microwave works, but I have some questions about a few of your claims. You may be right that the microwaves do not penetrate deeply into food. Electromagnetic waves tend to be absorb-able by materials -- provided the correct energy states in the molecules -- and it is not impossible that radiation might be absorbed before reaching the center. However, for standing waves to appear, reflection must be occurring. And if reflection is occurring, that implies that a reasonable portion of photons are making it from one side of the microwave and back -- probably multiple times. Now, this might be due to radiation that avoids the food, but then I would expect distorted node evidence within the food -- if any clear wavelength evidence at all. Electrons brushing the anode could refer to two things: An electron beam that only contributes a portion of its electrons to the anode at any given point and does so with a reasonably random distribution. Or an electron beam that gets close, but does not actually contact the anode. In either case, the electrons in the beam provide an electric field that changes in time -- which will generate a current. All materials exhibit dialectics, but to different extents. Water is useful because of its polarization, and it's heat capacity does allow it to absorb more energy per degree centigrade increase. However, I would think there is more at work than just heat capacity and polarization. For example, rotational and vibrational energy states being correctly spaced as to absorb photons.

[@EebstertheGreat]

Firstly, yes, the standing waves are only present when nothing obstructs them. Standing waves are not necessary when radiation is constantly being emitted and absorbed. However, without the reflective mesh lining the oven, any waves not pointed directly at the food would simply escape. Instead, they are reflected repeatedly until eventually being absorbed either by the walls of the oven or, more often, by the food. You will notice that he says the positioning of the nodes is unpredictable, and that is true. Their position is not exactly the same when different items are placed in the oven. That said, they typically don't move too much. But note that most modern microwaves rotate the magnetron to mitigate this issue. Either way, it is always better to rotate your food 90 degrees partway through cooking if your oven doesn't have a rotating platter. In your two example types of "electron beams," only one will produce a current, and the other is the one he shows. In reality, neither is correct. Electrons boiled off the cathode (don't ask me about the terminology here; I don't know why the terms used here are opposite the usual convention) do eventually reach the anode. If they merely came close to the anode and returned to the cathode, no current would flow. Current is produced when charges move from one end of a circuit to the other. That is in fact the definition of current. If charges do not move, current does not flow. The anode and cathode are not separate complete circuits coupled by a magnetic field, they are merely two parts of a single circuit. Again, a changing electric field _is not a current_. A current is a flow of electric charge. The vibrational modes of water are _not_ special with respect to microwave frequency. In fact, the resonant frequency of water is in the infrared region of the EM spectrum, as are the resonant frequencies of most of the other substances in your food. Water will absorb photons from anywhere in the microwave spectrum; in fact, they will absorb higher frequency radiation much better, but then the microwaves of course would not be able to penetrate as far, so the frequency is chosen as a compromise. This compromise may work less well for other substances, so that some may only absorb them very weakly and others may absorb them so strongly that only the outer layer is cooked. (Even 1 cm penetration is very important to cooking microwavable food!) This explains why not all foods can be microwaved, and why most microwavable foods have significant water content. But it has nothing to do with resonance. It is just basic frictional heating. This is all stuff you can look up very easily and confirm for yourself.

[@EebstertheGreat]

By the way, the compound rotational/vibrational spectrum of liquid water is very complicated, but is centered around the wavenumber 3400 cm⁻¹, corresponding to an absorption wavelength of about 2.9 µm, nowhere near the 12 cm wavelength microwave radiation used in the oven.

[@Jensaw101]

EebstertheGreat By conservation of energy, you're right. The photons must be absorbed by the molecules for heating to occur. The reflection is what it is, but the heating occurs through absorption. And if the photons can be absorbed by the food, it's likely to be absorbed by the food before getting to the center. Quantum mechanics compels me to consider this absorption in terms of kicking molecules into more excited states. Vibrational and rotational states, most likely. However, there is likely some quantum electrodynamics I am unfamiliar with that better marries what is observed and predicted in the classical model of this (mainly the electric dipole trying to follow an oscillating field). The cathode may well be called the cathode because it is a position of negative charge. Electrons are being boiled off of it. And if the electrons are to be attracted to the anode, it would need to be positively charged. Yes a current is the movement of charge, not the change of electric field. But it should be noted that a changing electric field produces an emf that compels charges to move. Still, it does seem like the magneton's design is meant to amplify the electromagnetic waves produced by the circular electron beam. Referring to it as resonance makes sense, at least in terms of analogy.

[@EebstertheGreat]

Jensaw101 Typically conventional current flows from cathode to anode, whereas it seems in the cavity magnetron it is the opposite (electrons flowing from cathode to anode, opposite conventional current). But I'm not sure why that is. Anyway, yes, water molecules do absorb microwave photons by exciting their vibrational and rotational states, as you would expect. In liquid water, this creates considerable friction as hydrogen bonds are stretched and broken, and it is this friction that heats the water. Similar things happen in other dielectric media, though not necessarily to the same extent. As for an emf compelling charge to move . . . either charges move from the cathode to the anode or they don't. And if they don't, the current is zero. And resonance is of course what produces the microwaves (the cavities in the magnetron are sized so as to resonate at a specific frequency), just not what absorbs them.

[@fryncyaryorvjink2140]

theres thorium in my microwave?! sweet, I'm going to collect discarded microwaves and build a nuclear car

[@computerassociates7686]

after you finish building the car, drive it on solar freaking roadways

[@deathcogunit106]

I laughed way too hard at this.

[@metalpachuramon]

Hahahaha someone is aware of the trending wet dreams

[@pickeljarsforhillary102]

And if you get thristy while driving you can drink from your solar powered self-refilling water bottle.

[@sebashtundakeng8683]

ye good luck

[@PatJones82]

The water molecules aligning themselves makes complete sense, and blew my mind. So cool. EXCELLENT VIDEO!

[@juniorcyans2988]

As a physics student, I wasn't interested in engineering before, but now I suddenly became amazed by it! I'd love to know more. Thank you very much for your concise and clear explanation!

[@TheEulerID]

The cavity magnetron was designed by two physicist's. Harry Boot and John Randall of the University of Birmingham in 1940 as the source of high powered microwave energy for "centimetric" radar, so this is an example of the physicists being involved in resolving engineering problems. It is not a lone example.

[@juniorcyans2988]

@@TheEulerID 😀Thanks! That’s why I decided to study physics: it’s behind all the modern stuff!

[@Kriegerdammerung]

The speed of light is 299,792,458 metres/second, not centimetres

[@engineerguyvideo]

+Kriegerdammerung we correct this in an annotation ... Sorry for error.

[@Kriegerdammerung]

I would say is approximately 186,278.230 mi/sec (Assuming 1 mile is 1.60934 km, if you want to get the figure yourself, an absolute value for an inch is 25.3999779 mm)

[@DatBoiAderbeen]

what are you in middleschool? you use metric in science classes

[@michalvalta5231]

*you use metric in science

[@acl1566]

As if converting to miles is going to give you a better sense of the speed of light... lol... smh.

[@NewMessage]

"You can get an idea of the wavelength of the energy emitted by the magnatron... using cheese." Best American science quote ever.

[@roytee3127]

Better yet - you can do the same with chocolate bars. I .e., "You can get an idea of the wavelength of the energy emitted by the magnetron .... using chocolate! (But his idea of using a pan full of grated cheese actually works better.)

[@TobyOnTube]

how did he know which two hotspots to pick in order to measure their distance? To me the pattern of hotspots seemed irregular. But since his cheeseplate did not rotate leaves me with the question why we have an irregular pattern of cold and hotspots. If there is a single standing wave in the chamber then the pattern must be regular with hotspots marked at regular spacings with the nodes indicating the coldspots. I don't get it. For a didactical demonstration it seems arbitratry to pick two seemingly random hotspots that conveniently are spaced 2.5" apart for the calc. of the speed of the EM wave. Anybody who can clarify?

[@rylalu]

@@TobyOnTube I'm assuming he is well read on the subject giving him essentially subconscious confirmation bias. He was taught where to look for the relation and unquestionably assigns his critique from his observations to align with his subconscious thought. He has not proven the existence of the wavelengths patterns but has indeed just re-affirmed his own subconscious correlation bias. Rather, he is not creating anything new, but anonymously observing what he already believes to be true. Whether this is how microwaves work or not is this is enough information to provide a tangible truth? If what he has been taught has involved any potential erroneous beliefs or theorems, this explanation is based off of all of those previous errors in judgement that have been passed down through collective knowledge. Essentially whether this is how microwaves work or not is based off of an attempt to understand observable and repeatable phenomena that was then passed down to him. Assuming he took every word as truth, as most do. Forthwith, if there were magic elves that produce the dancing wave forms, his result from his hypothesis would still be the same. There is always something more to learn about a subject which can break new light on a subject expanding our understanding. The belief that the fore front of researchers always know the truth is a bastardization of what it means to perform science. That being said, he is probably close to the truth, but he would never know if he was right since he is not trying to attempt to actually prove any of these phenomena. Most of the original research is hidden behind military DARPA confidential and top secret authorizations. Who knows how they did it. There is so much about modern interpretation of the physical universe we are not anywhere close to understanding. If you look back 100 years we do not believe 98% of the things they used to believe were true back then. Only things we still believe in are religions and even that's starting to change.

[@vivekk6241]

It’s mind blowing how many “ordinary” appliances we use daily that are in fact incredible feats of engineering. Thank you Bill. This is one of the types of content we should be exposing to kids while they’re in the sponge state of growing up!

[@AverageAlien]

I never use a microwave I'm not poor

[@winoles]

Outstanding simplicity your explanation has!

[@Iscrnd]

Amazing video! Mechatronic engineering student here, and I absolutely love your work :) Just a thought, you should have mentioned that the microwaves have rotating plates on the bottom to allow the food to rotate through the hot and cold spots, thus cooking the food evenly.

[@kjamison5951]

I have to subscribe to this channel! Three years at university and although I worked directly with magnetrons for two years, the explanation of how they work was never so clearly explained! Thank you!

[@EpicSelenium34]

1:48-2:16 I finally understand this for my chemistry class thank you!!!

[@younginf151]

I feel like he wants to sell me a microwave

[@Crazytesseract]

Don't buy it. Read my comment first!

[@uncannyvalley2350]

I bought 3!

[@badouplus1304]

@@Crazytesseract And what is your comment? I don't want to scroll down infinitely.

[@johnh1001]

Maybe he just likes frozen pizza in the microwave .

[@romanorleans504]

@@badouplus1304 r/woosh

[@ToddHowardWithAGun]

When I was a kid, I used to microwave cheese on a plate until it was crispy. Little did I know I was actually doing science.

[@saudiboy5136]

Thom then why did you do that for? u eat or for fun?

[@saudiboy5136]

thats madness hahaha

[@Radi0he4d1]

Roxy J And just like one porno said, everything is art.

[@Silvmatsu]

+Radi0he4d1 Sauce? ( ͡° ͜ʖ ͡°)

[@Radi0he4d1]

Silv999 I've lost it. It was a white guy in his thirties and a slightly younger black woman. She was visiting his house to evaluate pictures or something.

[@TheLast2nd]

I learn more from your channel than I ever have in school.

[@josephvictory9536]

I feel so so sorry for you

[@geico105]

Don't feel sorry for just him, feel sorry for 95% of American children. Our education system is the worst in the first world.

[@TheLast2nd]

I feel sorry for me, too. Schools here in the U.S. think it's more important to teach us the Pythagorean theorem, than to teach us how a microwave works or how to do taxes. 'Tis a shame.

[@TheAnarchySniper]

Should have listened in school then lol. Actually im from Australia so maybe the education system in America just sucks but I learnt similar stuff to this in school (e.g. How electric motors work)

[@johnperdue7541]

Joseph Victory Why would you feel sorry for this snowflake? I'm sure they still received a certificate and participation award......

[@riverwildcat1]

Very well done. You answered all the questions I've been storing up for years.

[@gerhardlesch3615]

The best video yet on explaining the microwave oven's principle of working. My time was not wasted on this one.

[@sinancothebest]

Yea, its amazing to me how mere humans came up with the idea and science behind using invisible waves to accelerate molecules to heat up and design a machine out of it. Microwave ovens are truly peculiar creations that defy conventional line of thinking.

[@irrespondible]

According to lore, the creator was working with Microwave generators for radar antennas and found out the generator's heat melted a bar of chocolate in his pants, then decided that this kind of heat transfer could be good for heating food and made the design here.

[@gmosphere]

you have a voice like butter.

[@philipvalenzuela4969]

Garrett Monie He can do a Voice over for The Series "Cosmos" check it out youll see what i mean =)

[@buddyclem7328]

I know. He's like Andy Rooney without the attitude problem! I could watch and listen to him all day.

[@johnperdue7541]

Garrett Monie So did Ted Bundy.......

[@rinislaboratories1315]

Or a voice like.... cheese?

[@guyjperson]

Dec 2023. You remain a favourite explainer of engineering. Concise and fascinating. Thank you, Mr. Hammack.

[@Bambuzzsprosse]

Sick man. I know this video is already older but these have been 5 of the most entertaining minutes in the last two months.

[@tysonwallace576]

Your videos are so informative, and clear. You are a great teacher, thank you!

[@nahidbonna6485]

Excellent explanation man. Respect to you. Please keep uploading these videos to make everyone unravel the true beauty and legend of engineering

[@dlkline27]

Having been a radar technician I understand magnetrons and waveguides but I've always wondered how the rf (radio frequency) energy is distributed inside the microwave oven. Now I know that if there is no rotating plate, hot and cold spots would be the norm. Thanks!

[@myriaddsystems]

Fantastically simple and effective presentation - now I understand - especially with the superbly illustrative example of blowing across the mouth of the pop-bottle. The most intelligent are the ones who can explain the most difficult-to-understand concepts such that anyone else can themselves understand - sheer genius! P.S. The cheese illustration was a masterstroke!

[@Nightwing22k]

Who else stops the Microwave at 1 second, so that it doesn't make the noise?

[@moderator8247]

Me

[@nflfanatic4life]

Heck yes I do. I don't want everyone else in the house hearing the beeping and then asking me for my food!

[@Whiteboytripping]

Aintnobodygottime for getting beeped at

[@snap-off5383]

oh c'mon who stops it that early, you let half at least of that last second go.

[@billgates1682]

My new LG sings to you so I don't try to beat the timer anymore, lol

[@mybluemars]

This is one of the best explanations I have seen on how the microwave tube works. Your amazing Bill. Thank You!

[@MakiPavlidis]

Love your understandable explanations, thanks Bill.

[@naturemedic5856]

Quick but complete and awesome way of teaching! Very cool.

[@saskiavanhoutert3190]

Nice to see how a microwave-oven works, thanks for explanation.

[@TheArcV]

Great video and I love the cheese experiment to show the wavelength! Might want to put a couple precautionary comment in the video though. 1) Don't take microwave apart unless you know how to discharge residual energy in coils which can kill you 2) don't cut or break into the magnetron as that can contain beryllium oxide which as a dust is dangerous

[@ChanChan-pg4wu]

Beautiful and classical explanation. Thumbs up!

[@sashrill]

did he just wink at us 4:45 ?

[@engineerguyvideo]

Likely I did: I like all of you.

[@sashrill]

haha well i went to a few of your other videos to see if you do that same thing. im actually quite ashamed of myself that i havent discovered your channel earlier.

[@sebashtundakeng8683]

xD

[@NeilCrouse99]

LOL,... I think one eye just closed slower than the other,... *: )*

[@ishangoel2194]

yep

[@rocketfuel204x5]

Wow. That was the best explanation I could of ever asked for. Like damn dude😂❤

[@mamartin2966]

Truly amazingly presented - thanks!

[@kamalhossain2267]

Amazing explanation and demonstration. Easy to learn.

[@TheArabsolga]

This made me instantly subscribe... Well presented and explained!

[@Dzia1ania]

+Plato Time travelling again, my old friend?

[@TheArabsolga]

Jay Konkol Well.... yeah....

[@DANGJOS]

+Plato Me too! I was just amazed at his incredible explanation, I just subscribed immediately

[@deerbirds]

It's 2 am and I have a lab report to write why am I here

[@randominternetprofile8270]

summer session 2?

[@tensorbundle]

it's 6 am and I didn't sleep whole night, sitting in my lab preparing for today's meeting with professor. How come I ended up here? oo magnetron did that

[@Orni37]

nerdswithfriends d'hiver n vs

[@stvia]

Because you felt the need to write an overused comment under a youtube video

[@jeffertron3973]

Relatable

[@bernardvreulink2457]

You have a GIFT of explaining science in an enjoyable and FAST way .... PLEASE make more videos. ;-)

[@jackeljefe3032]

One of my new fav channels. Thank you

[@taschke1221]

I'm always so amazed--how far humanity has come--when I watch your videos. I'm in tune with the "workings" of quantum mechanics, but it is unfathomable, the leaps and bounds we habe made to get here. I deeply appreciate your ability to humble mineself.

[@taschke1221]

have*

[@Stefan-jk5gx]

There wasn't really a need to show off your knowledge about quantum mechanics. Especially when it isn't really relevant in this video.

[@randominternetprofile8270]

not even the world's top physicists are in tune with quantum mechanics

[@kahlzun]

"If you are not completely confused by quantum mechanics, you do not understand it." - John Wheeler.

[@wolf335599]

Not humanity, white people.

[@tgguadarrama]

Great video. My thirst of knowledge has been satisfied

[@StevenYoungcaptual]

I absolutely love your teaching and great form of presentation 👍

[@dedede5586]

when you found the wavelength of a microwave through melted cheese, that's when i knew this truly was the greatest channel on youtube. amazing video!

[@KafshakTashtak]

This professor really knows how to teach.

[@zes3813]

wrr

[@3209explosion]

Well said Zes.... Well said.

[@seededsoul]

With the voice of Kelsey Grammar

[@johnperdue7541]

SAHM That's because, like most teachers and professor's, he couldn't make it in the real world.......

[@user-nx7sd1yi7q]

but he is an actual engineer, the fuck?

[@THERantingGerbil-gw4xg]

This really helped with my science project. Thanks!

[@johnh1001]

See the movie "My Science Project" you'll like it ! ! !

[@jwinchester9302]

This wizard science is straight up RIDICULOUS… thank you for the breakdown!! You’re awesome!

[@snogitsune2581]

This video answered finally to some of my questions!! Thanks, it was very interesting ✨

[@SomaElectricals]

If i broke the beryllium tube and left the room immediately without breathing can i return the next day

[@Rocketman88002]

@Soma, it would be best not to. Beryllium dust is very fine and moves easily.

[@christiancee6333]

Kinda like that cat in the box, is he dead? Alive? Or both?

[@username42]

no

[@spacebrain1944]

R.I.P Soma. We will remember your last post here

[@louistournas120]

The tube is not made of beryllium. That is copper. Notice the yellow red color. There is an insulation part, not shown in the video, that is supposedly made of BeO. Consumer microwaves most likely do not use BeO. They use Al2O3 which is much cheaper. There is probably some other metal dopent in it since they tend to have a purple color. However, don't take my word for it. I only heard this from another guy.

[@4lifejeph]

Magnetron was always my favorite Transformer back in the day.

[@louistournas120]

I think you are thinking of Megatron, the leader of the decepticons.

[@4lifejeph]

@@louistournas120 Yea it was a joke friend.

[@briancooley8777]

That’s what I was thinking when I heard magnetron lol

[@frankdick7040]

good teacher, active, clear, brief.

[@tygerbyrn]

Great video. Thanks for this clear and concise explanation. I look forward to more videos.

[@systempatcher]

Something we did in one of my physics seminars was put a damp paper towel in the microwave and then held it up to a thermal camera immediately after taking it out of the microwave. You can actually see the standing waves.

[@randominternetprofile8270]

great, now I gotta go buy a thermal camera...,thanks

[@systempatcher]

Random Internet Profile It was a quarter million dollar thermal camera so good luck.

[@whitcwa]

Mine cost $200. Lookup Seek Thermal or Flir. Android or ios.

[@randominternetprofile8270]

Chris W Well damn, I spent the last 5 weeks raising a million dollars on gofundme for my personal thermal camera.

[@johnh1001]

Back in the 70's I use to see extra large micro waves in peoples kitchens. They were so big and heavy it took 2 guys to lift them . One of those was an "Amana Microwave" . The heating compartment was quite large , I remember putting in a large sized pizza into it and the pizza came out great . But as the years went on the microwaves got smaller and smaller . At present , I can just barely fit a medium sized pizza into it and sometimes that won't even fit . It's only just occasionally now that I see large sized frozen pizza , but those would never fit into a present day microwave . Why did the microwaves get so small and stay small ? I would like to microwave a large pizza just like in the past .

[@bobbylee2853]

The good ol’ Radar Range!

[@johnh1001]

@@bobbylee2853 The good old Radar Range ! Yes , correct ! Back in those days most folks didn't know what a microwave was . Next to that were most likely folks that believed a microwave was a warming oven next were the folks that used the microwaves properly and next to that were people that truly understood microwaves , number of watts etc .

[@sid7852]

Brilliant, best educational method I have ever seen. Thanks.

[@VictorCharlesEvans]

Well done Bill, great explanation!!!

[@casualobserver3145]

Well that was interesting. So, when the microwave carousel turns the food, it is passed through areas of high & low flux changes such that the food is heated more uniformly. Amazing! Incredible technology exists all around us!

[@TheBjossi80]

Similar to 5g and now we are the food

[@casualobserver3145]

Icelandic Acro Team LOL! “How To Serve Man.....IT’S A COOKBOOK, IT’S A COOKBOOK!!!!”

[@TheBjossi80]

@@casualobserver3145 👍

[@RaduRadonys]

@@TheBjossi80 Except 5G hasn't got a power of 700W like my oven. Just saying.

[@KevinRoseYT]

From what I have understood from other explanations, the "cook from the inside idea" is a myth. Yes, they work deeper than conventional ovens, but the microwaves penetrate about 1cm; not right to the center.

[@SeattleScotty]

Yes that's correct; there is a lot of bad information in this video. Surprising considering how good this channel is.

[@engineerguyvideo]

Correct ... this is what I meant ... and thought I said in video ... one must distinguish between microwave heating (which is in principle volumetric) and its manifestation in a microwave oven, which as you note results in penetration of a cm or so.

[@fulfillmentcenter2637]

You explain clearly. Great video.

[@RudiKiefer]

Informative as well as entertaining. Thank you !

[@DouglasQuaid999]

I understand some of those words

[@jaloveast1k]

You reminded me that I wanted to clean up my microwave, thx.

[@adampzakaria]

Bill, one of the best science and engineering videos I've ever seen. Please continue to make videos 🙏

[@blackhawk-qy2rh]

First video I watched of yours and I subbed 30 seconds in. Awesome work. Keep it up

[@StephenJonathanSwift13]

That's why the plates rotate inside to evenly heat

[@BeccaTheBoring]

Just bought two copies of your book; one for me and one for my brother, since he has a habit of swiping my cool books. Question: are there any plans of releasing an audiobook version of it?

[@engineerguyvideo]

+Rebecca Gillan I assume this is Eight Amazing Engineering Stories -- let me know if it isn't -- we have plans for an audio version of a forthcoming book, but haven't thought of doing an audio version of this book. Audible seems to be the major player in audiobook: Is this were you would listen to it, or would you go elsewhere?

[@BeccaTheBoring]

+engineerguy yes, I am referring to Eight Amazing Engineering Stories. After seeing it mentioned in a video, I went looking for it at Audible but didn't find it. I tend to prefer "brainy books" as audio books because I seem to absorb the material better that way. I am enjoying reading it in Kindle format, though. I was just wondering if that might be coming in the future so I can keep an eye open for it.

[@Darquine]

+sdhjtge Just ain't found the method or material that is best suited to you. I use to hate math with a passion, until I graduated school and was stumbled across things like "The Nine Code", the Phi ratio and so forth. There's a way. Just have to want it enough to find that way. (^_^)

[@larrybentley9312]

Great explanation for microwave oven operation.

[@jamesdownunder701]

Thanks Bill, I learnt a lot in just 5 mins!

[@justicecountryman4060]

This is going to be recommended to so many people in about 9 hours.

[@engineerguyvideo]

Why?

[@justicecountryman4060]

@@engineerguyvideo because KZbin tends to recommend videos to people on a rhythm and I'm pretty sure this one will get recommendations. I may be wrong but I've guessed right before.

[@Ryan-op2ng]

@@justicecountryman4060 well it just DID!

[@justicecountryman4060]

@@engineerguyvideo I was a little off, but I was right. 2m more views :)

[@justicecountryman4060]

@@Ryan-op2ng lol

[@TheBanjoShowOfficial]

So that is why the plate spins, oh jesus thats incredible!

[@SpaceCadet4Jesus]

Nooo...the plate spins so the user can admire the food as it goes round and round. Like the carousels at a fun fair.

[@23CoSo]

Excellent explanation - well done.

[@saif.restifer.khomain]

Thank you sir for your coherent explanation.

[@Movie_Games]

Will we ever have a microwave that can cook my leftover pizza evenly? The outside is always overcooked and the inside is always cold.

[@grumpyauldman]

Movie Games ... you don't heat pizza in a microwave, you animal.

[@abhijithcpreej]

An oven that rotates can do that. Maybe. Also, try moving it around between the heating process so that the waves reach places it couldn't before

[@seabulls69]

Try using a fry pan. Works way better than a microwave.

[@Rig0r_M0rtis]

Man up and eat it cold.

[@ObscureStuff420]

Air fryers work good for reheating pizza. Set it to 325 for about 3 minutes or so.

[@Xendrius]

So invisible magic?

[@ratcrib]

witchcraft yes

[@hexajull3060]

Yep invisible milfs not magic

[@1BeGe]

@@ratcrib Depends on if it weighs more than a duck.

[@isentient666]

Wonderful explanation!

[@803mastiff9]

Excellent presentation.

[@MarchGreen]

So how does the brushing electron at the opening of the cavity creates electromagnetic wave? And since the tube is coated with metal, how does the electromagnetic wave propagates to the microwave oven's chamber? Could you please give a bit more detail? Thank you

[@Ravenwest19]

I have this questions too :(

[@SeattleScotty]

The cheese experiment was the real reason for this video, other than that it was just a disassembled magnetron and incorrect information. This video is surprisingly disappointing.

[@timstoffel4799]

The electrons represent a current across a resonant cavity formed by the copper walls. The electron current induces a field in the cavity that rapidly changes polarity, alternately aiding and opposing the electron beam. This creates the rotation shown. Every other cavity wall is tied together by a pair of straps not shown to make all the cavities resonate in sync. There is an antenna in each cavity that couples the RF energy in each cavity to a probe at the end of the tube. This probe couples the RF energy into the waveguide, and then into the oven cavity. The magnetron is actually a very old tube design, dating back to I think, the 1920's. Another microwave tube that operates by the cavity coupling principle, but is long and straight, is the klystron.

[@Balltime88]

3:53 the key parts are these two magnets where we destroy your speaker and ear drums.

[@abztract1]

I am laughing too hard and for too much time with your comment!!!

[@alexandrebriard9175]

Lmao

[@ZeroSpawn]

Scared the poop out of me!

[@buniculflorin]

amazing video, absolute delight

[@iateuranium-235forbreakfas7]

1:44 amazing how they captured footage of this happening

[@SuperPlatypus123]

Where do you get all your antique devices? In every video, it seems like you have some sort of cool appliance or item (the radio, film projector, etc.). Do you have all these laying around your house, or do you borrow them from somewhere just to do a video? It's very interesting to see them sitting next to their modern successors.

[@engineerguyvideo]

+Nolan T. We get them from wherever we can. This microwave was from target. Some of them we get on ebay -- the older pop cans, for example, in another video.

[@qtbshk]

+Nolan T. Product manufacturer are happy to give sample product to the people like EngineerGuy for the review they need for their products. Thanks.

[@aurorasinplex5947]

@@engineerguyvideo gov will have all heads for this tech thay teach us that we always have loss but never talk about the converted gain we can make from eletromagnets if u convert all the wast thermal energy around you u can use it universally as energy u need a true sine wave bipolar like the power comp dose a true pure sinewave like a grid tie inverter once the signal is made the system will turn on and consume wast thermal energy from the environment and space around you... there is free energy but it comes from Universal thermal loss and converted into a gain. so a pole Transformer and a microwave Transformer have a common between each other u can take 2 microwave Transformer provide a pure sine wave grid tie inverter to it or a true bipolar sinewave that inter acts with nature in a perfect spherical motion like a flower of life.. if ur home provides this use it as a Source signal then u can simply stack the Transformers on top of eachother in correct fasion and note that the 1 wire on the Transformer must stay connected and the other disconnected your only useing 1 wire on the hi side .. so test ur self 2 microwave transformer stacked on top of eachother same face sides. one side 120 to the wall and the other 120 side to what u want to power and useing the Transformer just the way it came out the microwave with the wire attached causes the energy in its perfect spherical motion to converted wast thermal energy to amp for u hot to cold in to out... should look a bit nuts with u use a form of wireless energy but its interacting with the environment...this is my work a compilation of Otis car. Tesla. and many other very smart people nowadays i think i found the gate source and drainif this gets out to much that it works the power comp and mib will have our headsdont do this at home warning high voltage yet i cant stop u lol DO NOT TOCH THE CORES OR THE WIRES OK u will die make sure u dont touch the core if the hi wire is mounted to it u dont have to mount the hi on the core if u dont want u connect the 1 hi wire to the same side hi on the other transformer then the core should besafe to handle if nessary

[@aurorasinplex5947]

@@engineerguyvideo gov will have all heads for this tech thay teach us that we always have loss but never talk about the converted gain we can make from eletromagnets if u convert all the wast thermal energy around you u can use it universally as energy u need a true sine wave bipolar like the power comp dose a true pure sinewave like a grid tie inverter once the signal is made the system will turn on and consume wast thermal energy from the environment and space around you... there is free energy but it comes from Universal thermal loss and converted into a gain. so a pole Transformer and a microwave Transformer have a common between each other u can take 2 microwave Transformer provide a pure sine wave grid tie inverter to it or a true bipolar sinewave that inter acts with nature in a perfect spherical motion like a flower of life.. if ur home provides this use it as a Source signal then u can simply stack the Transformers on top of eachother in correct fasion and note that the 1 wire on the Transformer must stay connected and the other disconnected your only useing 1 wire on the hi side .. so test ur self 2 microwave transformer stacked on top of eachother same face sides. one side 120 to the wall and the other 120 side to what u want to power and useing the Transformer just the way it came out the microwave with the wire attached causes the energy in its perfect spherical motion to converted wast thermal energy to amp for u hot to cold in to out... should look a bit nuts with u use a form of wireless energy but its interacting with the environment...this is my work a compilation of Otis car. Tesla. and many other very smart people nowadays i think i found the gate source and drainif this gets out to much that it works the power comp and mib will have our headsdont do this at home warning high voltage yet i cant stop u lol DO NOT TOCH THE CORES OR THE WIRES OK u will die make sure u dont touch the core if the hi wire is mounted to it u dont have to mount the hi on the core if u dont want u connect the 1 hi wire to the same side hi on the other transformer then the core should besafe to handle if nessary

[@aurorasinplex5947]

@@engineerguyvideo gov will have all heads for this tech thay teach us that we always have loss but never talk about the converted gain we can make from eletromagnets if u convert all the wast thermal energy around you u can use it universally as energy u need a true sine wave bipolar like the power comp dose a true pure sinewave like a grid tie inverter once the signal is made the system will turn on and consume wast thermal energy from the environment and space around you... there is free energy but it comes from Universal thermal loss and converted into a gain. so a pole Transformer and a microwave Transformer have a common between each other u can take 2 microwave Transformer provide a pure sine wave grid tie inverter to it or a true bipolar sinewave that inter acts with nature in a perfect spherical motion like a flower of life.. if ur home provides this use it as a Source signal then u can simply stack the Transformers on top of eachother in correct fasion and note that the 1 wire on the Transformer must stay connected and the other disconnected your only useing 1 wire on the hi side .. so test ur self 2 microwave transformer stacked on top of eachother same face sides. one side 120 to the wall and the other 120 side to what u want to power and useing the Transformer just the way it came out the microwave with the wire attached causes the energy in its perfect spherical motion to converted wast thermal energy to amp for u hot to cold in to out... should look a bit nuts with u use a form of wireless energy but its interacting with the environment...this is my work a compilation of Otis car. Tesla. and many other very smart people nowadays i think i found the gate source and drainif this gets out to much that it works the power comp and mib will have our headsdont do this at home warning high voltage yet i cant stop u lol DO NOT TOCH THE CORES OR THE WIRES OK u will die make sure u dont touch the core if the hi wire is mounted to it u dont have to mount the hi on the core if u dont want u connect the 1 hi wire to the same side hi on the other transformer then the core should besafe to handle if nessary