Microwave Ovens: How They Work, Safety & More

0.000000    5.900000     Welcome to everyday explained your daily 20 minute dive into the fascinating house and wise of the world around you
5.900000    10.880000     I'm your host Chris and I'm excited to help you discover something new. Let's get started
10.880000    15.520000     Okay, let's dive in think about the microwave oven sitting in your kitchen
15.520000    20.180000     It's probably the most used appliance that you think about the least totally. It's just there
20.180000    25.140000     It heats your coffee pops your corn maybe rescues a defrosted meal. It just works
25.360000    32.680000     But what's actually happening inside that box? How does this seemingly simple piece of tech
32.680000    37.040000     Zap your food warm. It really is a black box for most people isn't it?
37.040000    43.440000     We trust it, but the physics the history the engineering it's all actually quite remarkable
43.440000    45.460000     Yeah, and our sources today
45.460000    53.800000     Well, they offer a fantastic look under the hood everything from the fundamental science to you know the surprising origin story and the safety standards
53.800000    59.640000     Exactly, we've got a really interesting stack here insights on the physics from places like USC and commsall
59.640000    64.200000     Practical comparisons from coast appliances and the official word on safety
64.200000    71.640000     Straight from the FDA, right? So our mission is to pull the key nuggets from these figure out what you really need to know and give you
71.640000    77.600000     Well a complete picture of this everyday marvel. It's unpack it. So the name itself gives us a hint
77.600000    80.520000     microwave
80.520000    85.240000     What exactly are we talking about when we say microwaves in this context good starting point, right?
85.240000    93.360000     According to the sources microwaves are simply a type of electromagnetic radiation. Okay, radiation that word always sounds a bit scary
93.360000    95.360000     It can but don't let it scare you right away
95.360000    102.120000     Yeah, the electromagnetic spectrum includes everything you know low energy radio waves visible light then UV
102.120000    109.000000     X-rays gamma rays right microwaves just fit in the middle there wave lengths from about a millimeter up to a meter typically
109.000000    113.360000     Okay, so they're kind of like cousins to radio waves and light just different vibes
113.360000    116.320000     That's a good way to put it and here's a critical distinction
116.320000    123.840000     The FDA source really highlights this microwaves are non-ionizing radiation. That's key non-ionizing
123.840000    128.760000     What does that mean practically? It means they don't have enough energy to like knock electrons off atoms
128.760000    134.160000     Ionizing radiation like X-rays can do that potentially damaging cells directly
134.160000    138.760000     Okay, so it can't mess with your DNA in the same way X-rays might precisely
139.040000    147.000000     Not ionizing radiation like microwaves visible light radio waves. They just don't pack that kind of punch
147.000000    153.340000     Yeah, the potential harm for microwaves comes from heating tissue which needs really high exposure levels different
153.340000    160.120000     Mechanism gotcha and microwaves aren't just for reheating sad desk lunches, right? The sources mention other uses. Oh, absolutely
160.120000    162.000000     Beyond cooking
162.000000    167.220000     microwaves are fundamental to modern communications think satellite TV your phone signal right
167.220000    173.380000     They're also vital for radar systems which spoiler alert is actually how the whole cooking idea even came about no way
173.380000    178.000000     Okay, we'll get back to that. Yeah, and industry uses them too for drying materials vulcanizing rubber
178.000000    182.900000     They're incredibly versatile waves fascinating how one type of wave has so many uses
182.900000    190.140000     But okay back to the kitchen how do these waves the ones that travel through space or dry rubber somehow heat up my leftover pasta?
190.140000    195.220000     Where's the magic? The magic is really just clever physics according to the engineering sources
195.220000    202.580000     They point out three core things about microwaves for cooking first metal reflects them right no forks in the microwave got it exactly
202.580000    206.140000     Second, they pass right through stuff like glass paper
206.140000    212.660000     Many plastics okay third and this is the crucial bit they get absorbed by food absorbed okay
212.660000    218.140000     So that explains why the dish might stay cool while the food gets hot and the metal thing explains the
218.140000    224.980000     Metal box construction precisely the metal inside bounces the waves around creating this energy field
224.980000    230.320000     And the door has a special mesh screen that keeps the waves contained, but let's you see in
230.320000    234.620000     Clever and where do the waves themselves come from inside the box?
234.620000    237.300000     That's the job of a component called a magnetron
237.300000    241.740000     It's basically a vacuum tube uses electron beams and magnetic fields to generate the microwaves
241.740000    247.380000     Magnetron sounds important it is and most home ovens operate in a very specific frequency
247.380000    251.180000     2.45 gigahertz 2.45 gigahertz
251.580000    258.580000     Why so specific well the sources explain it was chosen partly because it was largely unused for communications back when ovens were developed
258.580000    266.340000     Plus it's particularly good at interacting with something called polar molecules polar molecules like north and south poles little magnets a bit like that
266.340000    271.500000     Yeah, molecules like water which isn't almost all food plus fats and sugars. They're polar
271.500000    277.260000     They have a slightly positive charge on one end slightly negative on the other okay now imagine these tiny polar molecules
277.260000    281.180000     Inside your food the microwave energy is this oscillating electric field
281.580000    288.300000     Flipping back and forth billions of times a second at that 2.45 gigahertz frequency billions of times a second
288.300000    294.520000     That's hard to imagine incredibly fast and as this field flips the polar molecules try to align themselves with it
294.520000    300.660000     They spin and rotate trying to keep up. So they're basically doing a chaotic super speed dance party in my lasagna
300.660000    309.780000     That's a great analogy and as they spin and jostle around in that crowded space they bump into each other create friction friction equals heat
310.100000    317.460000     Exactly that rapid friction-filled molecular mosh pit generates kinetic energy which we feel as heat
317.460000    321.140000     Aha, so the heat isn't coming from the air outside like a regular oven
321.140000    324.460000     But from the friction within the food itself you got it
324.460000    329.300000     The heat is generated wherever the microwaves are absorbed by these polar molecules
329.300000    336.340000     It's a fundamental difference though for thicker foods the sources do say heat conduction from those outer layers
337.020000    341.740000     Still plays a role in cooking the center. Right. He has to travel inwards to and
341.740000    347.140000     Crucially for anyone's still worried. Yeah, the microwave energy is converted into heat
347.140000    354.480000     It does not make your food radioactive or you know contaminated with waves good because microwave doesn't need to be followed by and glowing
354.480000    355.380000     Agreed
355.380000    359.220000     So we have these clever waves making molecules dance to generate heat
359.220000    363.980000     But where did this whole wild idea even come from it feels like something someone designed
364.260000    369.500000     But the history sources say it was actually an accident. Oh, I love an accidental discovery story lay it on me
369.500000    375.740000     This one's a classic. It's 1946 right an engineer named Percy Spencer at Raytheon is working on radar tech
375.740000    379.580000     Specifically those magnetrons we just talked about the wave maker exactly
379.580000    384.340000     So he's working near an active magnetron and the story goes you feel something odd
384.340000    390.660000     Reaches into his pocket don't tell me the chocolate bar. He'd been saving him melted a melted candy bar
390.660000    397.540000     That's the spark. That's brilliant. It makes you wonder what other great inventions were missed because someone just you know
397.540000    403.380000     Eight the evidence. Oh, true, but Spencer being an engineer saw more than just a messy pocket
403.380000    408.100000     He got curious grab some popcorn kernels put them near the magnetron
408.100000    416.660000     Pop then famously he tried an egg. Oh, please tell me it exploded it did all over a colleague's face apparently
416.660000    423.500000     Ouch, okay note to self and listeners maybe don't microwave raw eggs unless you're recreating history
423.500000    427.780000     We're cleaning up afterwards. Definitely a do not try this at home moment from the past
427.780000    432.380000     But yes, Spencer quickly realized this microwave energy was causing rapid heating
432.380000    437.900000     Raytheon patented the cooking idea in 46 and the first microwave oven was born straight away
437.900000    441.940000     Well, the first commercial one the radar range came out in 1947 the radar range
441.940000    447.260000     She sounds like something at a buck Rogers. It kind of looked like it too and was priced like it huge over six feet tall
447.260000    451.620000     Wait 750 pounds cost thousands of bucks not exactly counter-friendly
451.620000    455.580000     Yeah, that's more industrial kitchen or evil genius laboratory than my apartment
455.580000    459.460000     Exactly took time to shrink the tech refine it make it affordable make it safer
459.460000    469.420000     Raytheon introduced the first countertop home model in 1965 still pricey around $500 then but a huge step still a luxury item though
469.420000    475.940000     When did they really become the kitchen staple? They are today except and screw steadily the sources point to a tipping point in the mid 70s
475.940000    485.980000     By 75 microwave sales in the US actually surpassed gas range sales Wow by 76 more US homes had a microwave than a dishwasher
485.980000    488.780000     Convenience really one people over and now they're just
488.780000    495.380000     Everywhere expected, but they haven't totally replaced traditional ovens have they there's a clear difference in what they're good for
495.380000    503.140000     Absolutely that coast appliances source lays at a great comparison as we discussed the heating method is totally different internal molecule
503.140000    507.580000     Wiggling versus external heat and that leads to very different cooking results exactly
507.580000    514.240000     Microwaves are the undisputed champs of speed and energy efficiency for like small stuff for reheating need hot water fast
514.240000    516.620000     Microwave quick veggies
516.620000    524.380000     Microwave roasting those veggies for an hour oven right big potato maybe 10 minutes in the microwave versus an hour plus in a conventional oven
524.380000    530.260000     So for sheer speed and just heating things up microwave wins for many tasks. Yep
530.260000    535.660000     Reheating leftover is defrosting cooking things with lots of water veggies rice
535.660000    545.180000     Soup even you know scrambled eggs or those quick mug cakes and it's a big but for anything that needs that crispy skin or a browned crust
545.180000    548.540000     That's where traditional oven shine the sources are clear
549.100000    557.140000     ovens are way better for baking roasting grilling getting those textures. You just can't replicate in the standard microwave bread pastries a whole roast chicken
557.140000    563.980000     Yeah, you need that external heat for browning and crisping make sense ovens are just generally more versatile for a wider range of cooking techniques too
563.980000    569.620000     So they really complement each other speed and convenience from the microwave quality and versatility from the oven
569.620000    574.820000     It's not really a competition. It's a tag team a culinary partnership now speaking how they work
575.300000    579.140000     Let's tackle the perennial microwave problem the dreaded cold spot
579.140000    582.380000     Why is it so hard to get even heating ah?
582.380000    591.020000     Yes, the bane of reheated pizza you bite into a patch of lava right next to a chunk that's still basically frozen
591.020000    597.700000     What is going on there? Okay, this is where the physics gets a bit more complex the console analysis source dives into this
597.700000    601.740000     The key thing is uneven heating isn't necessarily a flaw in your oven
601.740000    606.040000     It's kind of an inherent result of how microwave energy interacts with the
606.040000    615.020000     Complexity your food. It's the food's fault my pizza's betraying me huh partly maybe and partly just the physics inside the oven cavity
615.020000    621.700000     First off different parts of your food absorb microwave energy at different rates right think of that berry pie example from one source
621.700000    629.060000     The berries are full of water the absorb energy super fast and get piping hot the drier crust absorbs less stays cooler longer
629.060000    635.780000     Okay, same thing with defrosting the parts that have thought the liquid water heat up way faster than the parts that are still frozen solid ice
635.780000    644.680000     Okay, so food isn't one uniform microwave sponge different bits react differently exactly and then the energy inside the oven isn't uniform
644.680000    651.520000     either as the waves bounce off the metal walls they interfere with each other creating these patterns called standing waves
651.520000    656.700000     Standing waves. Yeah, it results in predictable areas of high energy intensity hot spots and
656.940000    661.860000     Areas of low-energy intensity cold spots just sitting there inside the oven cavity
661.860000    666.980000     So there are literally zones of more heat and less heat just hanging out in the box
666.980000    670.460000     That's right if you just left your food sitting still
670.460000    675.100000     Parts would be constantly bombarded in hot spots other parts would be chilling in cold spots
675.100000    680.020000     Which is why most microwaves have the turntable the spinning plate to the rescue
680.500000    686.060000     Precisely the turntable rotates the food moving it continuously through these different hot and cold zones
686.060000    692.380000     It averages out the microwave exposure over time promoting more even heating. It would be much worse without it
692.380000    693.840000     Okay, that makes total sense
693.840000    697.840000     But you mentioned the food itself affects things too like there was a potato simulation
697.840000    701.060000     Yes, the cumsel source used a potato as an example
701.060000    704.780000     It showed how the food itself can act as a sort of resonance cavity
705.420000    711.220000     In something fairly uniform like a potato the simulation indicated the point of highest energy dissipation
711.220000    717.180000     Where the most heat initially gets generated can actually be in the center wait hang on so it can heat from the middle first
717.180000    722.820000     Sometimes I thought it was outside in it seems the initial energy absorption can peak in the center in some cases
722.820000    729.060000     But then another factor kicks in the foods thermal conductivity how well heat spreads
729.060000    734.360000     And many foods like that potato are actually pretty bad at conducting heat
734.860000    742.500000     So even if the center gets hot from absorbing microwaves that heat doesn't spread efficiently to the cooler outer parts through conduction
742.500000    745.340000     So the heat gets generated internally, but then gets kind of
745.340000    750.340000     Trapped yeah leading to hot centers and cold edges sometimes essentially
750.340000    753.980000     Yeah, and that trap moisture can get super heated turn a steam build pressure
753.980000    760.020000     And that's when you get those sudden bursts or micro explosions, you know when you reheat beans or fix sauce without stirring
760.020000    763.460000     It's like oh, yeah, the sauce volcano been there
763.820000    771.140000     Exactly so uneven heating is this complex dance between the foods ingredients the standing waves in the oven the turn table trying
771.140000    774.460000     It's best and the foods own slow heat spreading
774.460000    777.260000     It's not personal as physics. It really is
777.260000    782.900000     Now with all this talk of waves and energy and exploding food safety is obviously a big question
782.900000    788.220000     What does the FDA say about keeping these things safe? Right the FDA source is pretty clear here
788.380000    794.220000     They've been regulating microwave oven manufacturing since 1971. They set performance standards
794.220000    802.980000     Specifically to protect the public. Okay, so there are rules strict rules and the key insight from the FDA is that for a properly working microwave oven
802.980000    807.460000     Your biggest risk isn't some mysterious radiation leak causing long-term health problems
807.460000    812.220000     It's actually just good old-fashioned heat burns from the hot food or container. That's a relief
812.220000    815.220000     But also, yeah, be careful taking things out out
815.620000    819.780000     Exactly the main standard the FDA sets is a limit on radiation leakage
819.780000    826.420000     No more than five millawatts of microwave radiation per square centimeter measured about two inches from the oven surface
826.420000    834.660000     Five millawatts and the FDA considers that level safe. Yes, they state this limit is far far below the level known to cause harm
834.660000    842.580000     And the sources also note that microwave energy drops off really quickly with distance like stand 20 inches away instead of two inches
842.580000    850.460000     And your exposure is down to about one percent. Okay, so stepping back while it's running isn't a terrible idea just as an extra precaution
850.460000    852.540000     It's an easy-added precaution sure
852.540000    858.100000     Though the standards and safety features are designed to keep leakage well within safe limits anyway
858.100000    860.500000     Assuming the oven's in good condition
860.500000    867.740000     The FDA requires multiple independent interlock systems on the door interlock systems. What does those do? They're safety switches
868.340000    877.140000     Basically, they're designed to immediately cut power to the magnetron stop the microwaves the instant the door latch is released or the doors opened even slightly
877.140000    880.340000     And there's more than one usually two or three working independently
880.340000    886.020000     Plus there's a monitoring system that should shut the oven down completely if one or both interlocks fail
886.020000    892.100000     It's layered safety. So if the door is open, it should be physically impossible for the oven to actually produce microwaves
892.580000    899.940000     Correct and the FDA is very firm on this if your microwave ever operates with the door open stop using it immediately
899.940000    904.980000     Call them manufacturer or a qualified repair person. That's a serious safety failure
904.980000    913.140000     What about this other health effects people sometimes worry about tissue heating burns from the radiation itself cataracts even those potential effects
913.140000    917.620000     According to the sources are linked to exposure do very high levels of microwave radiation
918.180000    924.020000     Levels much much higher than anything you'd encounter from a properly functioning oven that meets FDA standards
924.020000    933.380000     Okay, injuries directly from the microwave radiation are extremely rare and usually involve like improper repair or deliberate tampering with the safety systems
933.380000    939.460000     Again, the vast majority of injuries involving microwaves are just thermal burns from hot food liquids or steam
939.460000    944.020000     So handle that hot plate with caution use oven mitts always good advice
944.740000    950.740000     And regarding pacemakers the FDA source mentions that while older models could potentially be affected by electronic interference
950.740000    953.380000     Modern pacemakers are generally well shielded
953.380000    957.220000     But if you have one of your concern definitely talk to your doctor sensible
957.220000    963.060000     Okay, so beyond checking the door works right and maybe not pressing your face against the glass while it's nuking something
963.060000    967.780000     What other practical safety tips do the sources give us what number one is always
967.780000    974.500000     Follow the manufacturer's instructions for your specific model right read the manual maybe huh
974.740000    978.260000     Yeah, also use only microwave safe cookware
978.260000    983.940000     We talked about metal reflecting waves using metal bowls or foil improperly can cause sparks
983.940000    988.580000     Anti-continue potentially damage the oven. Okay, microwave safe dishes only
988.580000    995.060000     Don't use an oven if the door itself the hinges the latch or the seals around the door look damaged or worked
995.060000    999.700000     That's where leaks are most likely if they occur check seals got it and check your manual
1000.340000    1005.460000     Some oven shouldn't be operated one empty it can potentially damage the magnetron in some design don't run it empty
1005.460000    1011.060000     Okay, what about that super heated water thing that sounds scary. Ah, yes, the erupting water phenomenon
1011.060000    1012.420000     It's real
1012.420000    1016.820000     If you heat perfectly plain water in a very clean smooth cup for too long
1016.820000    1022.340000     Especially if it's undisturbed it can get heated above boiling point without actually bubbling
1022.340000    1028.420000     It's called super heating and then if you disturb it like adding a spoonful of instant coffee or even just moving the cup
1028.900000    1031.380000     It can trigger sudden violent boiling
1031.380000    1034.020000     erupting boiling water
1034.020000    1039.380000     Not good yikes. How do you avoid that? The FDA suggests adding things like instant coffee
1039.380000    1042.820000     Sugar or even just a wooden stirr before heating
1042.820000    1049.460000     These provide nucleation sites little rust spots for bubbles to form normally preventing the super heating state
1049.460000    1053.700000     Or just heated for less time and stir carefully. That's a genuinely useful tip
1053.700000    1057.780000     I've heard stories about people getting scalded by that. It's a real though avoidable risk
1058.740000    1065.940000     Finally, just keep the oven clean food spills and splatters can absorb microwave energy potentially causing hot spots or even damage over time
1065.940000    1071.460000     Use water and mild detergent nothing abrasive. They could scratch the interior or damage those door seals
1071.460000    1075.140000     Extence and yeah, it's just regularly inspect the door the hinges the seals
1075.140000    1080.580000     If something looks bent cracked or just wrong probably best to get it checked out or contact the manufacturer
1080.580000    1085.940000     So safety really comes down to a combination of robust design standards enforced by the FDA
1086.020000    1092.340000     And then just basic user care and common sense precisely. It's a piece of pretty complex technology
1092.340000    1098.740000     There's been made remarkably safe and simple for everyday use through careful regulation and smart engineering
1098.740000    1105.780000     Wow, okay, so starting from just a box that heats food we've pulled insights from the sources covering everything from
1105.780000    1115.140000     Invisible electromagnetic waves and molecule dance parties don't forget the friction right and the friction heat to a surprisingly
1115.140000    1120.020000     Uh hot pocket adjacent accidental discovery. Thanks for his fan sir
1120.020000    1125.700000     How it measures up against old school ovens the actual science behind those frustrating cold spots
1125.700000    1130.100000     It's not you. It's the standing waves and the rigorous safety standards that mean basically
1130.100000    1134.180000     You're far more likely to burn yourself on the soup than on any stray radiation
1134.180000    1138.020000     It's quite a journey for something we just popped in or into without a second thought, isn't it?
1138.020000    1142.820000     The magic is really just fascinating well applied physics and some clever engineering
1143.220000    1148.100000     And now thanks to this deep dive into the sources you know why your food behaves the way it does in there
1148.100000    1152.420000     The science behind the speed and the diligent work that goes into making sure it's safe
1152.420000    1156.820000     So next time you hear that familiar dang maybe just pause for a second
1156.820000    1163.940000     Consider the billions of ways bouncing the molecules vibrating the turntable spinning the safety interlock standing guard
1163.940000    1169.860000     And maybe give a little nod to the accidental discovery that started at all with a melted candy bar and
1170.660000    1175.540000     One very surprised colleague, or maybe just appreciate dinner being ready in two minutes flat
1175.540000    1180.340000     Thanks for taking this deep dive with us and that wraps up today's episode of every day explained
1180.340000    1183.620000     We love making sense of the world around you five days a week
1183.620000    1188.820000     If you enjoyed today's deep dive consider subscribing so you don't miss out on our next discovery
1188.820000    1191.060000     I'm Chris and I'll catch you in the next one