January 20, 2020 100

Old-fashioned rice cookers are extremely clever

Old-fashioned rice cookers are extremely clever

I don’t know about you, but I find cooking
rice to be an extremely difficult task. Luckily somebody invented the automatic rice cooker and now all of my rice cooking problems have been solved! Hooray! Now, you might think that rice cookers are
a pretty boring small kitchen appliance. But actually, they’re among the… well, OK… If we’re looking at what they *do* then yeah, heh this ain’t no toaster, that’s for sure! But, while the device itself may seem pretty unremarkable, and indeed is, the principle by which it works is fascinating! Simply by exploiting one of the chemical properties
of water, this device can tell when the rice has been cooked, and the result is a perfectly cooked batch of the world’s second favorite grain. Assuming you got the water to rice
ratio correct, that is. So how does it work? Well, to find out, first we
need to learn a little bit about water. As I’m sure we all know, at sea level water
boils at 212 degrees Fahrenheit. Isn’t that just a delightfully easy number to remember? I don’t know what the heck that is in Celsius, probably some silly arbitrary thing, but anyway that
number isn’t the whole story. You see, water doesn’t just boil at that temperature. It *starts* to boil. See, if you got a pot of water on the stove,
and you watch its temperature rise with a thermometer, well what do you suppose happens once it gets to boiling point? You can see the temperature steadily rising as it approaches, so you might think that once it hits boiling point the water will just *poof* disappear and turn into a big ‘ol cloud
of water vapor. But of course, that’s not what happens. The temperature just plateaus,
and it won’t go any higher. But the stove (or hot plate) is still dumping energy into
the water, so why isn’t it getting any hotter? The answer is physics, and more specifically
the principle known as the latent heat of vaporization. This is a fun concept important to many fields
of study, from meteorology to refrigeration. Also known as enthalpy of vaporization, this
is the amount of energy required to transition a liquid into a gas. And it’s a LOT more
energy than just raising the temperature of that liquid (boiling of water starts to becomes audible)
OK, what we need to understand here is how latent heat differs from sensible heat. Sensible heat is something like, oh I dunno 68 degrees? That’s a a pretty sensible room temperature– Ohhh, oh, Sensible, like can be sensed. Got it.
(though it is still spelled “sensible”) Sensible heat
is the figure we can sense, or measure. The thermometer is looking at the sensible heat
when it tells us how hot something is. But as the water (or any other substance) reaches
its phase change temperature, adding energy into it will not raise the sensible heat. Instead, that energy gets absorbed by the molecules to free them from their liquid state,
and that takes a heckuva lotta energy. (boiling gets louder)
We don’t need to be too worried about that extra energy right now. We’ll get to that when we tackle air conditioning and refrigeration. But what you need to know for the purposes of cooking rice is that liquid water cannot
exist at a temperature higher than its boiling point. Dumping more energy into it will simply
make it boil away faster. It will not make it get any hotter. So what does that have to do with cooking
rice? Well, see, cooking rice is all about making water hot so that the rice will absorb
it and the starches convert to the other… things and all that jazz. And that rice is cooked
once it has absorbed all the water. You don’t want to keep cooking it after that point or
it will burn, and you don’t want to not cook it long enough or you’ll have rice
al dente which I’m pretty sure isn’t actually a thing. So, in an ideal world, we’d have a way to
tell precisely when that rice has finished cooking. And, thanks to latent heat of vaporization,
we do! See, water can’t get hotter than its boiling point. But cooked rice can. And once you know that little factoid, you can easily make a device which will cook rice to completion, and automatically stop. This is a very basic rice cooker. It cooks rice… and that’s it. None of that fancy multi-function nonsense. Side-note – I actually have a nicer rice cooker with a whole electronic interface thing that can do fancy things like slow cook
or steam vegetables but it’s got one of those gasket deals going on in the lid and frankly it
gets really gross all the time. And it’s a pain to clean. Now I’m not certainly someone
who eats rice as a staple food but when I discovered that this cheap, basic unit had just a
plain glass lid and both it and the bowl are dishwasher safe, I was like “Life Changer!”
and bought it on the spot. Truthfully I prefer it to my fancier one by a large margin simply because it doesn’t get gross and it cooks rice just as well, which is all I use a rice
cooker for anyway. Plus it doesn’t beep incessantly for 15 seconds when it’s done, so that’s a nice plus. Sometimes basic is in fact better, but that’s all down to your personal priorities and preferences, and I’m sure you all tell me why my priorities
and preferences are wrong! Anyway, this device is so incredibly simple and yet entirely automatic and I just love that sort of thing. At the bottom, you’ve
got a round heating element with a little button thing poking up through the center. This guy is spring-loaded and is the heart of its automatic operation. The rice cooker has two modes:
Cooking, and keep warm. Whenever it’s plugged in it’s in the warming mode. If we flip it over and take off the bottom,
we’ll see that there’s a buncha wires. In the keep-warm state, current comes in through
the power cord, and passes through this big resistor to limit the current before going
through the heating element. The lever to engage cooking is attached to that button
thing, and importantly it closes these contacts. This bypasses the resistor and allows the
heating element to run at full power. In this case, it’s a mere 300 watts. This is after all a tiny little rice cooker. Also, this changes which of the little neon indicators lights up. Useful! You’ll see that right now I cannot get the lever to
stay engaged. That’s because the button thing isn’t depressed. This serves as a
safety feature to prevent the heating element from operating at full power if the pot were
to be removed. Ordinarily the weight of the bowl would press down on it, but in this case
I need to substitute my fingers. With it depressed, you’ll see that the lever will now stick in the down position. What’s keeping it there is a permanent magnet,
which you can just barely see here. And this is where things get really interesting. The magnet is sticking to the bottom of the button, and it’s overcoming the force of a second
spring inside the button trying to push it away. Which, luckily, it manages to do. But here’s the thing about magnets. Get things hot, and suddenly magnets don’t work anymore. Uh-oh here comes a
Blanket Statement Abatement Alert! Magnets are confusing. Ferromagnetism. Paramagnetism. Curie points. There’s just
so much that hurts my brain. So, please do not assume I’m an expert here, ‘cause I’m not. Regarding this magnetic phenomenon I’m about to describe, this is my very best interpretation
from what I’ve uncovered through looking at patents, a very rudimentary understanding
of magnetic interaction, and also some forum threads where people were arguing about this. If I’ve gotten something wrong here, please correct me in the comments. And also, please check to see if someone else has already provided a correction, thanks. All magnetic materials have what’s called
a Curie temperature, or Curie point. For ordinary ferromagnetic materials, once you reach this temperature they cease to be ferromagnetic at all. In the case of a permanent magnet,
if you get it to the Curie temperature … you’ve broken the magnet permanently. So now it’s a permanent not-magnet. But materials that are attracted to permanent magnets will regain their attraction once they’ve cooled back down. This button thing is made of an alloy that
has a Curie temperature just a bit higher than the boiling point of water. This allows it to function as a temperature-dependent
kill switch. Thanks to the outer spring, it’s
always held firmly in contact with the bottom of the pot, which ensures it and the pot are
at nearly equal temperatures. So long as there’s liquid water sitting in that pot, the pot
itself cannot get hotter than water’s boiling point. This means that the button remains
magnetic, and the magnet is able to overcome the force of the inner spring,
so the device stays in cook mode But, once the rice has absorbed all of the
water (and / or once all the remaining water has boiled away) the energy being added to the pot by the heating element is no longer being absorbed as latent heat. Now, the pot can quickly
start to exceed the boiling point of water. And once it gets past the Curie point of that
little sensing button, the magnet is no longer attracted to it, so the spring overcomes the magnet and… *click*
the rice cooker switches back to the warming mode. Now, I don’t know about you, but I think
this is some of the most amazing ingenuity out there. This incredibly basic device is not only exploting the physical properties of water, but also the physical properties of magnetism
to automate the cooking of rice in an elegant and effective way. Sure, my fancier rice cooker
may have some fuzzy logic and a microcontroller in there, but anybody can program an Arduino
with some inputs and outputs. So this is much more interesting, at least I think so. These days, only the most basic rice cookers
continue to use this method of automation. But, for decades this is just how rice cookers
worked. I’ve tried to find when exactly this method was first put into production, and short of looking through every rice cooker related patent out there, the answer isn’t obvious. However, it’s been in use at least since the late seventies, having come across this patent. And you might be surprised to learn that rice
cookers are a rather recent invention. When you consider that we’ve had mechanical refrigeration for over a century now, it can seem a little weird that it took until 1956 for the first automated rice cooker to appear on sale in Japan, produced by Toshiba. Those early rice cookers used a sort of double boiler to indirectly heat the pot. Everyone’s favorite source
of knowledge claims that that went out of style in the 1960’s but, citation needed. Anyway. That’s it! I hope you enjoyed this
video. While I wouldn’t necessarily call this device
Automatic Beyond Belief! it is certainly among the most clever forms of automation out there. Even if I have to push the lever
down. And of course, thanks to everyone supporting the channel on Patreon, with a special thanks
going to these nifty people scrolling up your screen. CED part 5 is coming soon, so be on
the lookout for it! For now, though… eat up! ♫ insensibly smooth jazz ♫ I don’t know about you, but I find … the teleprompter to be a little finicky today Their among… well ok, if we’re looking
at they d .. yeah no I don’t like THAT take So, in an ideal world, ( makes weird noises as he checks his shirt ) So, in an ideal world… It cooks rice. And that’s it. None of this
… pbbbbttptt But, once the rice has absorbed .. bleuw I just noticed an error. We’ll try to fix it Materials that are attracted to permanent magnets will regain … pbbpbpbppb
(this one was excessive) Hey, it’s me! The SPIRIT OF THE CREDITS! Usually, I’m the SPIRIT OF THE ENDSCREEN but the shoot went real well and there aren’t many bloopers. So now you get to spend more time with ME!!! And I’m here to tell you that you’re a pretty cool human! Well, and I suppose there could be some non-humans watching, too. You’re all cool! Oh, wait, but y’all need to be able to read to see this part. Does that mean the SPIRIT OF THE ENDSCREEN can’t talk to animals? Goodness isn’t this an existential crisis? And so is reaching the end! AUGH!!

100 Replies to “Old-fashioned rice cookers are extremely clever”

  • Jarvis Stark says:

    It is not a silly arbitrary thing in Celsius. It is 100 Degree Celsius. It is not some retarded units system. It is SI.

  • ZygyKoz says:

    Now I just want to know what is the 1st favorite grain?

  • Blue Carbon says:

    68° is the perfect room temperature.

  • Colin King says:

    Hey, we got one o dose!

  • a. y says:

    Forget Fahrenheit!
    This is the 21st century!

  • NikkoDaniels says:

    The simplicity and sheer elegance of design is probably the reason my basic rice cooker(same company), around 20 years old, still works flawlessly!

  • Ronald Leckfor says:

    It can also be permanently damaged, ruining the magnet if the points stick together and the mechanism super overheats well above 212 degrees F reaches the hotter point and permanently neutralizes the magnetism in the magnet, even if the mechanism is basically intact and not melted down.

  • Jeffrey Pia says:

    Now if they could only find a way to automate the rice / water ratio. For those of us without fingers anyway.

  • Jane Doe says:

    I actually have that very same rice cooker haha. I love it for the same reasons you mentioned! The more "luxurious" ones look nice, but way too over-the-top for just cooking rice. Also, I don't need some useless "steam vegetable" option when I can already do that with just a basic rice cooker… can even throw in slices of taro into there and have them come out fully cooked.

  • sciencetoymaker says:

    "…I don't know what that is in Celsius–probably some silly, arbitrary thing…" All of your scripts are interesting and funny. Well done as always–thumbs up!

  • chugkingchris says:

    The Sound when it’s cooked is the best?!

  • subhankar biswas says:


  • Ozdave McGee says:

    Your cheap basic unit. I bought one in 95. It died 3 yr ago. I replaced with cheapy same exact brand as yours waa like $30. I have rice 3 times a week. They just go and go and go

  • Daw says:

    2nd favorite grain?!

  • Jerome Morrow says:

    In the Far East, the basic rice cooker remains king for the very reasons you mentioned – a simple glass or stainless steel lid, and bowl that can be easily cleaned. The fancy units have fixed lids and gaskets that get awfully sticky and painful to clean!

  • Igor Patricio says:

    I'm amazed cause few years ago, observing this machine I supposed they had a small thermometer inside that checked if temperature wasn't above 100C, that if so he'd stop the heating.
    Now im happy to know I wasn't so far away from being correct

  • Roland Jupiter says:

    CED please

  • Ren Huynh says:

    If your gasket dealy is getting gross all the time, it could mean you're not rinsing your rice well enough.

  • Hermes The sarcastic motorrad says:

    i thought im watching a captain disillution video, cuz he looks like him…

  • Racker26 says:

    you ran out of blooper "reel" early?

  • Kevin Day says:

    Cooks perfect rice 🤣🤣🤣🤣

  • Elena says:

    Technology Connections makes Smarter Every Day look a hillbilly from Alabama

  • Sun Jara says:

    212 Fahrenheit is 100 in Celsius.

  • A I says:

    Everything's wrong lol

  • Nico says:

    Technology Connections: Rice Al Dente isn't a thing
    Hell's Kitchen: Hold my risotto

  • abetusk says:

    I don't quite understand this. So when the water evaporates the temperature starts to go past 100C and demagnetizes the magnet (goes past it's Curie point), tripping the switch…but isn't the magnet now demagnetized? Does it remagnetize somehow? Does it not spend enough time past the Curie point to permanently demagnetize? Does this mean the magnet will eventually lose is magnetization through prolonged use?

  • Sam Digisphere360 says:

    Classic Technology Connections! Great video! I enjoyed no effort December, but definitely look forward to these types of these videos. 5 stars 🤣

  • finnigan16 says:

    So do rice cookers not work properly in Denver Colorado?

  • kabay0 says:

    Water-to-rice ratio? No problem!

    Finger technique.

  • Charles B says:

    Cool video, but I am assuming it was just poor humor that 212 was an easy number to remember and 100 Celsius was arbitrary

  • r r says:

    Guy pretends to be smart yet doesn't know the boiling point of water in Celsius……..my oh my

  • Allan Ashby says:

    Water boils at a hundred degrees Celsius — in most of the world. Of course, in the US and a few other backward places, it boils at 212 degrees Fahrenheit.

  • AnythingKid123 says:

    I have one

  • Jason Lieberman says:

    Thank an engineer 🙌

  • cat moth says:

    I’ve got one of these janky rice cookers and I’ve always kinda wondered how it works. Thanks, science👍

  • ItsAlxx says:

    Your priorities and preferences are wrong.

  • Stephen Yang says:

    This isn't old fashioned enough! The double boiler ones still exist, though they haven't made up the majority of the market for a very long time. The newer 1970s-ish designs like in this video, have a habit of scorching the rice at the bottom at times, while the double boiler never does, due to the way the outer water of a double boiler transfers heat at a constant 100C and never more.

  • Matt Andrews says:

    I just love that this is the exact rice cooker I’ve been using for months now. And now I’ve learned aaa lootttt. Fun stuff.

  • Nicolas says:

    While we're in rice cooker topic, how does it know the rice is cooked? Is it by weight or timer?
    I mean, no matter the cup of rice I cook, be it 3 or 5 cups, and with equal in water, it cooks perfectly. It doesnt get burnt, like if I were to used coal or stove burner… By using stove burner, I maintain a low-heat.
    I'm sorry if I dont make sense. But it has been a mystery to me 🤔🤔

  • Coil says:

    Excellent explanation, and a fascinating principle on which that cooker works. Embarrassed to say I finally got that latent heat thing a bit clearer! Thanks!
    Also, I just realized I need one of those (basic) rice cookers 🙂

  • Nick says:

    I came here for the corrections.

  • Susan Farley says:

    Rice all dente is a thing, but no one ever said it was a pleasant thing

  • Alvin Ng says:

    Craziest coincidence, not 24 hours after I watch this video, my mother is complaining about how weird it is her rice cooker isn't working, how it just keeps going to "keep warm" instead of cooking. Knowing the temperature factor now, I ask her if she recently used the container. She confirms she did accidentally use the container without water so the container was super hot. Took the container out for a few minutes, cooled down, reset and voila, works again. The more you know

  • timrepairs says:

    Me: 3 Mins into the video. Hmm, this guy is smart . Hits Like. Hits Subscribe.

  • Kelly Bailey says:

    Digging the WS shirt and EC mug!

  • Marshall Harrison - Guitarist says:

    Wish I had a mute button on my “rice cooker”

  • Frank Oettinger says:

    212 degrees is a silly arbitrary Number. In Celsius it is 100 for boiling and 0 degrees for freezing. Nothing to remember.

  • TreadwellJay says:

    4:31 SO agreed on needless beeping of appliances!

  • Golf Nut says:

    Nice… I always wondered how mine worked.

  • Whydoineedanamegoogle L says:


  • Grampamurked says:

    BORING! Yet for some unknown reason I watched all of it lol

  • Hansen Li says:

    Water boils at exactly 100 Celsius, the Fahrenheit is the silly one

  • Pimp Daddy says:

    I didn't care for how rice cooker works. Now that you say something about what temperature the rice cooker and magnets work it blows my mind

  • Caddy 1983 says:

    Will Technology Connections ever come out with a video on how microwave ovens work?

  • Personified Regret says:

    i like this guy

  • guy remote says:

    Thanks for explaining! Finally I understood how rice cooker works many thanks 🎉🎉😀😀

  • JD vlog says:

    we Asians are forever grateful for who ever made Rice cooker 👏🏽❤️

  • shinto666 says:

    Celcius would be a nice number to know, since the majority of the world uses it.

  • Kingsley Albano says:

    648 people didn’t understand this

  • The sinner Jim Whitney says:

    Man, I'm an electrician who loves both science AND cooking, and I've never even considered how these damn things work. I've never owned one (really don't see a lot of difficulty in making rice on the stovetop), but I've seen a blue damn billion of them. I just assumed they had a timer, awesome video, thanks!

  • Thomas Luggiero says:


  • Gio' Guidi says:

    Amazing simplicity.

  • IrenicusFTW says:

    mmmmm c8… tasty nonstick coating

  • 1979mackdriver says:

    In my experience and I'm no chef . But when it comes to kitchen appliances or utensils the first question I always asked myself .. how easy is it to clean and sterilize, I've always had good outcomes the simpler designs are often your go to . I've had a pressure cooker we got for a wedding gift in 1958 still use for making stew . I have the same Aroma rice cooker and it's easier to clean by a long yard I had a real fancy one that told you ratios and cook times and temps , but it was gasket Sealed and was difficult to remove gasket and clean inside the gasket seat .

  • Ion Zion says:

    Man sounds like Mickey Mouse

  • childrenofbodom33333 says:

    Hold up…. this guy hasnt popped in my recomendations for a year or so because i stopped watching science/educational videos on youtube..
    Earlier this evening while i was finishing my shift, i thought to myself "hey you should watch some of them engineer and electrician videos like you used to" .
    I arrive home – shower – bed – youtube – BAM! … that video top of the list.. they listening to our minds now uh?

    P.s great video btw

  • Jake Furey-Rosan says:

    That's so cool

  • Seth Lankford says:


  • S C says:

    Quick to cook and slow to burn, rice is patient, rice is kind, it does not boast..

  • Paul Esterline says:

    I have one of these! I love it and always puzzled how it knew the rice was done! Is this hot a hot pot that boils water works as well? It seems similar.

  • Davis Hatler says:

    You’re wrong and handsome

  • MisterMonkeySpanker says:

    "Permanent not magnet" love it.

  • whattheschmidt says:

    Future rice cooker improvement:
    Cook the rice until 1/3 of a teaspoon of water is left in the pot, now those 40 grains won't stick to the bottom and it will all be perfect and edible!

  • ruzzell907 says:

    The simplicity of a rice cooker makes it brilliant.

  • Conor Smyth says:

    everytime i see your channel i think i’m about to listen to metric

  • Prakhar Srivastav says:

    00:50 greatest jokes.

  • William Schock says:

    first time seeing you and I like being told how much im going to tell you your opinion is wrong. welp. im annoyed.

  • 555WEST says:

    Great Video 🙂 I own a rice cooker of the same brand and style but the bowl is made of Stainless Steel instead of coated aluminum. Extremely Reliable and durable appliance.
    Thanks again for explaining how it works I have always wondered about that.

  • pike666db says:

    Came for the explanation. Stayed for the sass and sarcasm.

  • BaronSilver Baron says:

    Rice cookers are a waste of time. Threw it away. My wife cooks rice in a frying pan with a lid and it turns out perfect every time.

  • Kuldirongaze says:

    212 degrees F….. which is why Celsius is infinitely better. We are made of mostly water. Water freezes at 0 degrees C and boils at 100 degrees C. Super easy. Super relevant. Also proteins (human) denature between 40 and 50 degrees C. So there's that.

  • Osiris Abreu says:

    0°C= Freezing point of water or 32°F
    100°C= Boiling point of water or 212°F

  • T33K3SS3LCH3N says:

    How do so many people seem to struggle cooking rice?
    1 cup rice, 1.5 cups water. Heat at max until boiling, stir until the water level is just barely covering the grains anymore, turn off heat, put on the lid, wait 10-15 minutes, done.

  • Kees Ankerhout says:

    Back in my day we called rice cookers ‘bombs’ and we would throw them on large Japanese cities

  • dcsensui says:

    I always wondered how it worked, and now I know. Also, it give any rice-cooking novice some important information about how to cook rice: Boil until the rice is no longer submerged. Then very low heat for another 15 minutes or so.

  • LelouDX says:

    Yeah, bitch! Magnets!

  • booyaa kashaa says:


  • AlphaDango says:

    Water boils at 212F <-> 100°C
    Water freezes at 32°F <-> 0°C

    I prefer Celsius

  • Artur Nizdzinski says:

    Water boils in 100 degrees of Celsius, it's even simpler to remember than in imperial units.

  • Shubham Nishad says:

    In India, in like 80% homes (in my rough estimate through observation of small set of people) we have this simple rice cooker only. Very few people have the newer ones. Some people even cook vegetables in it after putting salt and many spices in it. Having salt in water will obviously change the boiling point. In fact non distilled water naturally have salt. If they are based on boiling point, how come they still work?

  • liuzhou says:

    Immature, patronizing prick. I learned this stuff in high school many years ago!

  • Prison Mike says:

    I should be sleeping

  • Geddo says:

    I have used the same Hitachi rice cooker since 1976. Considering it has been used on average at least 300 times a year, the switch on it has been flipped at least 12,000 times, and hasn't failed yet.

  • Vivian Tristesse says:

    This is a thoroughly irrelevant comment, but I care about you and I think you need tteokbokki in your life! Go make some!

  • HaydenX says:

    I have a simple rice cooker similar to this one…but, for some reason, the parts aren't dishwasher safe. You'd think that resistance to heat and liquids would be enough to be DW safe, but I presume it has something to do with the chemistry of DW detergents…maybe surfactants? I don't know. I do know that while it's called a "rice cooker" it also does an equally good job with buckwheat, but not millet, quinoa, or oats.

  • SaimonSSL says:

    100 years later this magnet based price cooker will still be in the market. However the fancy digit one won't be and it is because digital products always gets outdated with bugs and replaced with a newer model.

  • blackmagick77 says:

    I already love my rice cooker but damn. I never knew it was this interesting.

  • megamanusa5 says:

    that cooker would burn rice at high altitudes

  • boeingnz says:

    No thermostat, that's cheating.

  • TronicJohn says:

    Praying to the SPIRIT OF THE ENDSCREEN from now on

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