Why can't you put metal in a microwave? - Aaron Slepkov

Dig into the science of how microwave ovens use electromagnetic waves to heat your food, and what you should avoid cooking in them.
--
In 1945, engineer Percy Spencer was standing near a RADAR device that produced high-intensity microwaves and noticed that his candy bar had melted. He then exposed popcorn kernels to the magnetron device, and sure enough, they popped. Soon after, the first microwave oven became available, using the very same technology. So, how does it work? Aaron Slepkov explores the science of microwave ovens.
Lesson by Aaron Slepkov, directed by Yuriy Polyashko, Darvideo Animation Studio.
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Animator's website: darvideo.tv
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Thank you so much to our patrons for your support! Without you this video would not be possible! Nevin Spoljaric, Sid Chanpuriya, Anoop Varghese, David Yastremski, Noah Webb, Roberto Chena, Oliver Koo, Luke Pisano, Andrea Gordon, Aleksandar Donev, Nicole Klau Ibarra, Jesse Lira, Ezekiel Raui, Petr Vacek, Dennis, Olivia Fu, Kari Teffeau, Cindy Lai, Rajath Durgada Manjunath, Dan Nguyen, Chin Beng Tan, Tom Boman, Karen Warner, Iryna Panasiuk, Aaron Torres, Eric Braun, Sonja Worzewski, Michael Clement, Adam Berry, Ghaith Tarawneh, Nathan Milford, Tomas Beckett, Alice Ice, Eric Berman, Kurt Paolo Sevillano, Jennifer Heald, Megulo Abebe, isolwi, Kate Sem, Ujjwal Dasu, Angel Alberici, Minh Quan Dinh, Sylvain, Terran Gimpel, Talia Sari, Katie McDowell, Allen, Mahina Knuckles, Charmaine Hanson and Thawsitt.

[@hyperviper0126]

From a literal military machine to a household device. Just shows inspiration is limitless and beyond who expects ?

[@micahbush5397]

That's pretty common, actually. War can be a pretty strong incentive for research and development.

[@berankb]

@@micahbush5397 Very true,things such as computers and modern medicine would be farther away now.This is also true for things like the space race

[@casjean8904]

@@micahbush5397 velcro!

[@danquaylesitsspeltpotatoe8307]

This was nearly as informative as the TED Talk why you should not smash your hand with a hammer!

[@AloisAgos]

Yeah, nearly all innovative tech started out as "how can we use this new technology to kill our enemies?" Before we had nuclear power plants we had nuclear bombs. Before we had GPS, we had spying devices. Before we had a knife for carving, we had a knife for stabbing.

[@madcat789]

Invisible Gnomes,.cmon, we all know this.

[@maddgrampa]

Gotta go to work. Work all day.

[@hyperviper0126]

I agreed. no argument and case closed

[@owlson2527]

Oh my god it’s cthun

[@user-er1ih6xt9x]

We're related 💀

[@yanguskhan8513]

Man tough gig they got. Eleves get to make cookies, gnomes works the waves man.

[@luckymo_on]

The thing is you CAN put anything in the microwave whether you SHOULD is the question here...

[@perpetualbystander4516]

You can't boil eggs though, 'cause then you'll end up with a terrible mess.

[@perpetualbystander4516]

But of course, you could...

[@Ya-boy-BoM]

Egg go boom

[@powpuckmobile9226]

Can put a house in a microwave oven. Checkmate

[@supportpossum5672]

@@powpuckmobile9226 just need a small enough house or big enough microwave oven. You absolutely could.

[@itsblonk]

Ah yes, TED-Ed giving me answers that my intrusive thoughts wanted to know.

[@Sara-eh4ln]

now I want to know what happens if the metal spoon touches the oven's wall

[@cdi_king_harkinian]

​@@Sara-eh4lnIt explodes

[@marianoguy]

So now intrusive thoughts is just regular thinking?

[@Kaity143]

@@marianoguy I think it should be expected because of how misused the word is.

[@marianoguy]

@@Kaity143 yeah, it's misused to this extreme. If used to describe regular thoughts it loses all meaning

[@6Twisted]

3:56 So you're telling me I shouldn't push my face up against the glass to watch it?

[@Philippines1943]

Yeah, and that's funny because when your mom forced you to get out of your house, she got fined for littering.

[@factchannel945]

kzbin.info/www/bejne/e3XRoqGkZs2FlZI

[@kronoxodus319]

@@Philippines1943 What a useless comment, please find a job.

[@alexandermcclure6185]

@@Philippines1943 Yeah, and that's funny because nobody asked for your opinion.

[@hazardeur]

@@alexandermcclure6185strange comment. its youtube comments, he can comment as much as he likes, even if you donßt agree with it

[@hotskoz]

My first experience with a microwave oven was in the early seventies. I took a job at a restaurant and someone handed me a large can of hot fudge topping and told me to put it in the microwave to heat it up before pouring it into the warmer. They failed to mention I needed to put the fudge in a bowl first so I just opened the can, put it in the microwave and turned it on. Moments later there was a lightning storm firing between the can and the walls. Interesting to watch but probably not too cool for the microwave. A second funny microwave story. My daughter, when she first moved from home, decided to make baked potatoes. She put two potatoes in the microwave and, remembering we always cooked baked potatoes for an hour, set the timer for sixty minutes. She then left to the mall. She came back an hour later to find the fire department had busted down her door and were setting up large fans to clear the dense smoke from her apartment. Lesson learned. Great video.

[@alannamichel5627]

Omg 😂

[@Ath3nx_2]

ded rn💀

[@nguyenson7073]

60 mins is crazy, 6 mins at high power is enough to smoke those 2 potatoes 😅

[@zmnicvander]

Some 25 years ago my Mom, a coworker of hers, and I went to a convenience store to get instant noodle soup for lunch. Back then the clerks were still managing food preparation, so this one clerk thought that the 3-minute cooking on the soup meant 9-minute cooking if she put the 3 soups together. Of course, the soups boiled out of their cups, the noodles exploded inside the microwave, and it was a mess. The clerk had to clean it up and start from scratch - without charging us double for her mistake. Lesson learned, I hope.

[@hotskoz]

@@zmnicvander Great story.

[@1998ichigokurosaki98]

It is scary how many people think that that radiation is dangerous. Some even avoid the microwave oven at all

[@wocky661]

Should we tell them their radiator isn't making them nuclear mutants?

[@catdogmousecheese]

Well, anything that generates heat is technically radioactive like humans are radioactive because our bodies are constantly generating heat.

[@Pingwn]

We should all just live in cave in conplete darkness because light itself is radiation and the light we can see has even higher frequency than microwaves.

[@justaguy4311]

Microwaves make food taste funny

[@AliceP.]

I feel attacked

[@thecooleraliguar]

they fire waves and they go whooooooosh and then heat. Super simple

[@supereldian]

The reason microwaves have that mesh screen on the door is to allow users to see inside and to prevent the electromagnetic waves from escaping. The electromagnetic waves are too big to exit through the small mesh screen on the door.

[@agnieszkacz_]

Oh damn, that’s actually a really neat piece of addition microwave knowledge 😯😯🤔☺️

[@shubhrajit2117]

Faraday's cage

[@michaelweaver4718]

Went to an engineering school where we had to measure the size of the waves. Essentially, the size of a pencil. If you compare that to the mesh screen, even if you remove the metal between two of the holes, the wave still cannot get out. It takes a slightly larger hole, as a bit of redundancy is built in so you do not microwave your face (although your eyeballs will notice them first.)

[@marzukimalik2241]

It's almost 3am, I can't sleep, and suddenly this pops up. Thanks!

[@QUBIQUBED]

wow, science makes you sleepy?

[@leolow2057]

​@@QUBIQUBED wow someone can't read

[@Colinnn.]

@@leolow2057wow someone’s rude for no reason

[@WaveRider1989]

Time to heat up some pizza rolls 😂

[@holokyttaja5476]

Electroboom tried it in a video and it is arguably harder to get something violent to actually happen than to just get a fork or a knife that is really hot.

[@ScotianSouthy]

I was looking for the informed comment.

[@HayTatsuko]

I love the art style and narration in this. Thanks for making such a lovely presentation!

[@pumpkinhead002]

You can put metal in a microwave. They even come with metal grates in them sometimes. Eddy current do happen, but it's generally a non issue unless you have something really conductive like aluminum, copper, or gold, and that metal is rough or crinkled. If you put a spoon in the microwave, say like you are stirring your soup and too lazy to remove it. Nothing bad will happen. You won't even get hot spots

[@bushputz]

I've worked in a lot of commercial kitchens. If we needed something heated quickly and didn't want to fire up a burner, we just threw it in a stainless steel 1/6 pan and nuked it. It's fine unless you leave a metal spoon in it or put a metal lid on it. Lots of people I worked with made that mistake - once.

[@JasonTheOneAndOnly]

I put my face right up the glass when I hungry, am a dead man.

[@pedro92073]

😂

[@suprnova23]

You know that little metal matrix/ grating on the microwave door? It prevents any waves from leaving the microwave. They just get bounced back in. I wouldn’t worry about it ✌️

[@alexandermcclure6185]

@@suprnova23 It reduces them exponentially, not perfectly blocking them. This is why there is also a thick layer of glass between the mesh and the outside, too. Still best to sit at least a couple inches away, though.

[@user-pw3df9jd7x]

1. from a military machine to a necessary household device 2. how does a microware oven operate 3. different food's composition will have different effects 4. not all of microwaring metal is dangerous

[@factchannel945]

kzbin.info/www/bejne/e3XRoqGkZs2FlZI

[@KnowArt]

lovely animation

[@jaredlee6591]

Such a beautiful style

[@MatubbarAzadAvijit]

Many myths surrounding the microwave oven have been discussed in this video. Very good one. Thanks. 👌

[@brawlwith_me]

I love this animation style.. Good Job👍

[@nimaybolar]

Great video. Always wondered this.

[@noname_noname20]

Loved it❤ Amazing explanation

[@masterdna117]

perfect video to watch after or before electroBOOM's video on microwaving metal

[@alial-jassim2504]

"Microwave is safe" "experts recommend to stay a few feet away when cooking"👁👁

[@pedrojorge1912]

"to totally limit exposure, experts recommends..." There's no harm being lightly exposed, but if you want to avoid exposure nonetheless, stay a few feet away.

[@ronin1648]

@@pedrojorge1912 There's a mesh on the screen door that should prevent waves from passing through.

[@gailaltschwager7377]

Thank you!

[@terence602]

Never put a banana in your microwave while texting your friend

[@grapeshott]

Time travel is a myth

[@margaretwordnerd5210]

That is so oddly specific I can't stop visualizing how you learned this. It's the intellectual equivalent of being Rick-rolled. Well played.✌🖖

[@redshankyman4181]

El Psy Congroo

[@terence602]

@@grapeshott The organization has brainwashed you.

[@terence602]

The organization is deleting my replies 💀

[@SharowbladyeGaymerPorate]

I absolutely love TED ED Keep going team!

[@1luvAdriana]

Love the animation ❤😊

[@Kirnotsarg]

4:05 This is what I wanted to know. Thank you!

[@briantaylor9285]

Amazing.

[@freebirdy333]

Man i literally was wondering about how do microwaves work a few days ago, thanks 😂🙏🏻

[@user-xx7pq4xj4l]

Love the animation

[@noahahmed5821]

So thrilled to see a Steven Wright joke as the opener!

[@ajchapeliere]

One of the baking KZbinrs I follow did a demo on making ganache in a stainless steel bowl in the microwave. They've said it has to be stainless, which makes at least some sense. Stoneware retains a lot of heat, so it's easy to overheat the ganache and break its emulsion.

[@paytonturner1421]

The video on microwaves is interesting when you dig deeper into the science of it.

[@Hollowdude15]

Great video TED-Ed :]

[@minanabil-sg1ku]

very informational

[@jforster29]

There are two dominant heating mechanisms: dipolar rotation and ionic conduction. I have been studying the application of microwaves for assisted comminution of ores and we have demonstrated excellent results! Microwaves can selectively heat sulphide minerals in rocks and this causes differential thermal expansion between the grains and microfractures to occur in the rocks which allows for a reduction in ore competency and an increase in the liberation of valuable minerals.

[@caotranvu4799]

this one is so good

[@YamenNazer]

Wooooooow i loved the animation TED-Ed😍😍😍.. does anybody know what programs used to make such video?>

[@kidbonesonline]

Ted Ed out here asking the REAL questions.

[@4h4nn]

If you reverse the rotation of the rotating plate, you can use the device to build a time machine.

[@lzrx]

XD

[@zodiacfml]

I just saw a recent microwave video from a few days ago. I'm now certain TED-ed gets their choice of topics browsing youtube. Microwaving tips they gave about metals like spoon or forks very accurate from my experience

[@Michaelonyoutub]

Microwaves heat *liquid* water, they aren't actually that great at heating frozen water, which is why frozen things often don't heat that well and heat unevenly. If something frozen is in a microwave at room temperature, parts on its surface where water might have warmed up enough to thaw due to the air around it, get cooked and then thaw the areas immediately around it allowing them to get cooked, while frozen areas surrounded by more frozen areas, remain frozen and experience no thawing/cooking. Eventually heat from areas that initially thawed and got cooked, reach the frozen areas and thaw them, but by that point the initial thawed area is likely over cooked. That why when cooking something frozen in a microwave, you should first leave it out to thaw a bit so it cooks evenly, or alternatively, find some way to warm it up above freezing with hot water or something before cooking.

[@empyreum6869]

or you use the defrost setting.

[@raeldri5867]

3:57 if it was the intent why put a window that allows me to watch my hot pockets cook? 😅

[@KJchanel88]

Wow it is amazing to watch this,,, now we know

[@KingOfTheChoppas]

4:05 for the part about metal

[@paramgalib040]

No way Ted Ed posted a video on something I just Googled an hour ago 😮

[@daitins]

Thank you

[@RealFoxTrotFox]

Thank Ted-ED for answering questions I ask myself at 3am

[@qowalapundit3171]

thanks for great educational vids, btw who was the narrator? Mr. Slepkov himself?

[@user-ww8jf1ib5v]

damn interesting. (peak content keep upp ted edd)

[@abrarjahin8848]

I actually am doing a project about microwave and magnetron and yeah i eventually came to this part

[@maeannengo4908]

Please do a video about magnets since some people believe magnets do not work underwater

[@atticusspontaneous]

Awesome!

[@FreshBeats2]

Cool

[@DoneDragon1]

Whats crazy is that since there are effectively no moving parts, anyone trying to figure out what it does without knowing about radiation would assume its magic lol

[@schoolvilleOfficial]

The Animation is nice

[@VegaTheLyra]

The amount of things in this world that are only possible because water is polar is insane

[@Smolstarfish]

Ted Ed: Why can't you put metal in a microwave? Me: Yeah, why not? 😡

[@danielfrancisco2341]

My microwave has a little sticker reminding me to put a metal spoon in if I’m heating liquids to avoid superheating

[@kiwilonewolf]

Great talk, except that radar technology was already in use before Percy Spencer appeared on the scene.

[@zillurzakaria3407]

Thanks

[@SteveFrench_420]

Yup... I was just about to say I've left spoons in there before as he said it at the end. Good video

[@deadlypyre]

Hey TedEd, can you please make a video on Music Conductors and its history over the years ?

[@migu8328]

No! I'm gonna stare at my microwave eyes anninch away from the door

[@ghoust592]

Thankfully Microwaves now are made with metal grating, radiation is not able to penetrate the grate since the waves are too big for them to escape

[@cattameme]

Ceramic bowls are so mich nicer and feel better quality. I love my ceramic set.

[@vaclavnovacek1035]

If the magnetron melted Spencers candy bar how come it did not burn him, or at least made him feel the warm?

[@jorgemtzb9359]

It did, or at least it should have. chocolate bars don't need that much heat to melt but yes, in effect he was being cooked alive... just, barely.

[@adrianblake8876]

Assuming the candy bar was chocolate (which is how I always heard the tale), it melts at just above room temperature... I've had chocolate melt in my pocket on warm days...

[@jeanmarc6517]

"I dont understand, how can the sun melt this chocolate bar...but not me??" Because we transfer heat around our body and sweat to expulse heat, unlike the candy bar.

[@ajchapeliere]

To add a bit to the *first comment: If the waves from the magnetron in the room were primarily being focused upwards to look for aircraft, I think only a small amount would be "leaking" into the room itself, so to speak. Chocolate itself is also... Kinda wild as a material. It has a low melting point and the structures it forms when it solidifies are based on how hot it got while it was liquefied. I'm guessing the difference in composition and size might also be a factor. The human body is mostly water with some proteins for structure and from a scale perspective it's much bigger than the chocolate bar. If you want to dig a bit further into any of it, I recommend finding some videos about "specific heat" (Crash Course or one of the other STEM channels should have something). I'd also recommend videos on tempering chocolate and making ganache. Sorry if I'm coming off as ranty, I get a bit excitable when the random information in my head might have a use *and* lines up in ways I didn't expect 😂 Stay curious, my friend! *Clerical edit: some of the other comments weren't displaying when I initially said "previous"

[@ajchapeliere]

​@@jeanmarc6517that's not very good logic. Firstly, the heat transfer from the sun comes from other parts of the electromagnetic spectrum; some frequencies of microwaves can't even get through our atmosphere because the water vapor and other molecules and particles reflect or scatter them. Secondly, sunburns are basically our skin getting cooked by the sun's UV radiation. This probably has less to do with how our bodies regulate temperature and more to do with where the microwaves were focused and the difference in water content and overall mass between the person and the chocolate bar.

[@user-ux2ml6rn7q]

Ive a NEFF microwave and i can put a metal spoon in mine as look as it doesn't touch the side walks , in fact it telm you to do so when boiling water or soups

[@525Lines]

My favorite steven wright joke!

[@reinefantastique]

Hello my dear friend! thank you for the cool video! keep filming! I'll wait for new videos

[@Frootyloops629]

Its 100% safe but don't stand close to it

[@anneakah]

If you heat through oven or microwave and eat it you can easily feel how the oven fluid tastes better

[@arcie3716]

I kept remembering that AWOG episode where one of the characters (I think it was Darwin) left a spoon in the microwave and the house exploded

[@RudieObias]

I love my science oven!!

[@clementlettuce]

art style omgg

[@KafshakTashtak]

Correction : microwave doesn't vibrate molecules. The energy of the microwave photon is in the range of rotational energy of molecules, so it rotates them.

[@jonbilgutay2]

In my experience, food cooked in a microwave cool faster then food headed on a stove or in an oven.

[@Hollowdude15]

Wow

[@nathalie_desrosiers]

I still prefer the taste of oven cooked food over the micro-wave. And the problem with micro-wave, is that it never warms uniformly.

[@jazz6711]

That explains why when I put a little water in my leftovers, it heats up better

[@zeonb]

This still doesn't explain why we get a hot plate with cold food after heating it

[@tastethejace]

Metal impurities in the plate

[@margaretwordnerd5210]

If a dish or cup is hotter than the food, it isn't microwave safe. Tastethejace is correct about metal impurities. It's not fun to get a 2nd degree burn from a mug handle. Note the unsafe dishes and never microwave them again. Check the bottom for manufacturer labels saying it is or isn't safe, but many don't say. Dishes older than 1980 are frequently not microwave safe.

[@perpetualbystander4516]

Plates are known for being greedy heat absorbers...

[@margaretwordnerd5210]

@@perpetualbystander4516 It isn't about the shape of the dish. Try microwaving a plate made of paper, plastic, or ceramic without metal. Does the plate get hotter than the food? Now microwave a different shape that is lead glazed pottery. That can get dangerously hot. Watch the video, they explain it well.✌🖖

[@perpetualbystander4516]

@@margaretwordnerd5210 Oh, it seems I forgot to add a suitable smiley to go with my previous comment. Here it is: 😜 But thanks anyway for the info I never asked for. 👍

[@jonathanmorris2452]

I usually remove the metal dishes from my pies. I once didn't and when it touched the edge of the microwave oven or when one dish touched another dish then it looked like the sparks from a welding machine.

[@user-wy9go4lx2r]

Wait, if spencer's chocolate melted, and popcorn and egg cooked, why wasn't spencer getting affected by the microwave at all?

[@calexprenas]

I leave a spoon in my oatmeal soups gravies etc every day and have for years. If the food isn’t liquid enough it can cause burnt areas so only do this with liquid-y dishes!

[@xBananowyJEx]

Ah, the science propaganda. We all know that microwave ovens work on MAGIC~

[@mateo-adventures]

Amazing

[@orena932]

Does the microwave interacting "strongly with water" have to do at all with the microwave frequency and water's resonant frequency?

[@ruanrobert00]

About the opening sentence "I put instant coffee in a microwave oven and almost went back in time". The general theory that if you go fast enough you can move through time. It's possible that he was alluding to the combination of speedy microwave ovens and instant coffee. Probably seemed funnier in its time when microwave ovens were new.

[@SuparNerd]

Imma go microwave a bowl of soup with a spoon in it

[@maia.papaya]

so if u put a dehydrated food in the microwave, it wont even feel warm after?

[@simonmeadows7961]

The definition of an intellectual is someone who can watch this video without thinking of Gremlins.

[@lo_oil]

اتابع القناه عشان اتعلم انجليزي بس المعلومات حقائق مثبته او نظريات فقط؟؟

[@GregorWSky]

4:01 how much is a few feet in centimeters?

[@stardewofpyrrhia4381]

A few feet is about a meter :)

[@OwoLyn]

So, what is the answer for this question " why can't people put metal in the microwave"?

[@dgr8nikhilsrivastava]

fun!!!

[@mateuszcielas3362]

can anyone explain how material of magnetron isnt depleted if losing electrons?

[@sergiusima1142]

The material does not lose anything, the electrons come from and go to the power source and magnetron is just as a conductor from this point of view.

[@mateuszcielas3362]

@@sergiusima1142 okk

[@stardewofpyrrhia4381]

Electrons are bits of energy, so the materials stays while they come and go :)

[@JohnWayneRiveraDoculan-oj7lo]

wow

[@JuanGonzalez-nn6dw]

Wonder what effects the radar magnetron had on that guy, I mean if it melted the chocolate and we are also made of mostly water?

[@pretzelbomb6105]

It made him slightly warmer. It doesn't take much heat to melt a chocolate bar. He could have achieved the same effect by standing close to an active stove.

[@jeanmarc6517]

There's literraly a giant ball of fire producing much more dangerous type of radiation in the sky under wich you pass most days...Its the same thing without the dangerous radiation...

[@leontarkostas5768]

the microwave in my home even recommends leaving a metal spoon when microwaving liquids, i did it once without a spoon milk spilled everywhere

[@Ki1aGam3z]

“Soon after, the first microwave oven became available” Ahh yes, a Ted Ed classic line