+Physics Videos by Eugene Khutoryansky Actually the RF seal on a microwave is tuned to the magnetron's frequency(2.4 GHz) to reflect that frequency back to the inside of the box instead of shorting it out. It's a common technique used in radar transmitters.
It is very hard to stop microwaves from leaking through the door seals. 2.4GHz is almost like water. It leaks everywhere. The gap in the door is considerably smaller at 700 mhz than at 2.4ghz, so the seals work better at lower frequencies. Also, the transmitter for the wifi is only a few feet away. The transmitter for the cellular is miles away. The signal strengths are vastly different.
another thing is that microwaves just stop a lot of the power of the signal. that is what cooks the food. the power not the frequency. im actually surprised that the phone didnt work in all of them.
actually that makes sense why it worked in some but not others since when they were further from a cell tower or wifi router the power of the signal would be lessened thus allowing the microwave to stop it verses when you are closer it cant stop it as much.
Great, my friend watched this video with me and all she took from it is that the microwave leaks radiation. She completely ignored where you said it was non ionizing and is currently trying to cover the microwave with "protective foil" Thanx Diana. I guess the good news is, after she's done entombing the microwave, she won't have enough tin foil left to make a hat.
For those of you who are wondering what this comment is about. It actually refers to an anime called "SteinsGate", in which a microwave acts as time-machine
I remember dragging an HP spectrum analyzer home from work back in the 80's to do this. Most of the leakage was at the door joint. Holding the door tighter there was less leakage so I adjusted it. The internet was a university novelty then, mobile phones were mounted in the trunks of doctors and lawyers and everything over 1 GHz was a small fortune.
I’m wondering how much the H-Field might play a role here. A Faraday cage, like a microwave oven, is more effective at blocking the electrical component of the electromagnetic radiation. But the magnetic component usually goes straight through the shielding unaffected.
@@Aj3.14 why must every comment by a science RUclipsr include a reply by somebody who's shocked that similar people watch each other's videos? If anything, I find it interesting that James used his Shorts account to browse, rather than the original one or something more incognito. (More seriously, that emoji seems to imply you're disappointed. That's even more strange than being surprised by somebody famous.)
Years ago, I powered up a radar detector with a power adapter and tested to see if it would pick up a signal from the microwave. It did. It showed up as X band, which was around 10 GHz.
H I think you are probably right but if the microwave did act as a faraday cage at 700MHz anything is possible. Although the wavelength is considerably shorter at 5GHz.... I'm rambling now. I'll stick to playing at 7MHz.
+Physics Girl Have you checked the smartphone was still on the 2.'4GHz network AFTER removing it from Samy's microwave? Because it could have quickly switched to 5GHz as the 2.4GHz faded away.
What I appreciate most in the video is the the final discussion about bias in the observation and the sample was not homogeneous in the other characteristics :)
As an avionics technician, I have performed leak tests on microwave ovens installed on aircraft. When I was performing these tests in the late 80's, EVERY microwave I tested leaked beyond acceptable limits. I was actually surprised to see microwaves that did not leak.
+Physics Girl Note that Wi-Fi also uses the 5GHz band. If his wireless router supports it, the facetime call could have used 5GHz, not 2.4GHz thereby penetrating the microwave.
Interesting to see those experiments really done. Thanks! The reason WiFi was getting through better than cellphone signals could be that the cell tower was a lot farther away than the WiFi access point. Even though cellphone towers emit more power and have better high-gain antennas (they radiate most energy horizontally and only a little bit upwards -> poor reception in airplanes), the inverse-square law means the it is likely that a lot less less cellphone tower field intensity was arriving than WiFi field intensity.
+YouCanScienceIt But, as she stated herself, she ignored too many variables to make it a good research. It makes nice watching, but the research was crap, haha. Fortunately she says it herself too.
It's possible your iPhone used the 5 GHz wifi signals when it was in the microwave. That would explain why it still received the call when the microwave was (supposedly) blocking the 2.4 GHz signal. Also, thumbs up for the Applied Science t-shirt! :)
I'm glad you mentioned the position, orientation and distance away of the microwave from a cellphone tower, because it makes a huge difference. Cellphones can tolerate variations in received signal power of around 60dB which is a factor of one million. So an oven allowing a millionth of the signal in from a really close tower might be the same as no Faraday cage at all if the tower is at extreme range. Still it's mlldly worrying that any measurable amount of 2.4GHz energy escapes. Thanks, I enjoyed it. Bill Dixon
I actually work in the industry and we use microwave ovens for testing. It used to be that you could unscrew the antenna and put in a coax cable to connect to the cell hardware but external antennas disappeared. Note that in the US voice calls would use CDMA band classes 1 and 2 at 850 MHz and 1900 MHz (PCS) and sometimes the auxiliary 800MHz range. But for testing LTE data which runs in the GHz bandclasses we place the mobile UE in the microwave and run an antenna wire inside from the eNodeB. This prevents the UE from attaching to a commercial signal and our testing from affecting any users of the commercial signal. We are not allowed to bleed any RF. Another interesting fact is that some high efficiency energy saving windows are very good at blocking LTE radio ranges. So much so that I have seen a demonstration where a mobile was placed less that two feet from from the eNodeB antenna and one of those salesman demonstration mini windows placed between them. The mobile lost communication immediately. So if you are getting a bad signal inside the house doing the "natural" thing of going to the window could be the worst choice to make.
Lead and other metals in glass and tint would be the likely culprits. Security mesh and heating elements may compound that. The average residential wall should generally block less RF than a typical window. Where I work the mess hall (the only place we're generally supposed to use personal phones) has a decorative aluminum grid overhead to diffuse lights and act as a ceiling, somewhat hiding ducts and whatnot. Have to go into another room (which is full of windows, lol) or outside to get useful call reception. e.e (It's a "clean" factory, so we don't just walk outside.)
Thanks for the information. I have read to put one's emergency radio and electronic equipment in an old microwave oven with the cord cut to protect against an EMP, and told to test it in a similar manner with the FM radio band on. Now, I have my doubts. Your test is good for people as a cheap way to check their microwave oven. Thanks. Good luck with your site.
Samy & Dianna, best team ever. I love Samy's channel for all of his infosec, and Dianna's for science. Surprise surprise to see them both. Also way to represent the hackrf! Great video.
The issue may not be between microwaves, it may be the signal strength of the surrounding cell phone towers that your phone is communicating with. To be sure you should gather the different microwaves in the same place, and see if the results are the same.
Thank you humble man for the men-explaining. Science Girl literally said that variables such as placement of microwaves, age, cellphone towers nearby, and etc could have affected the experience... We, the people of science, all know it was just a simple demonstration, not study for a publication... I wonder if was a man you would come here and bluntly correct the demonstration and ignore the fact that the possible interference of unknown variables have been mentioned 😒🤡
One thought: if you considered the microwave oven as an attenuator rather than a perfect cage, you would definitely see a different picture. Your WiFi network is much closer in proximity than the nearest cellular tower and thus your reduction in signal strength might be the same, but still have enough to make it through eventhough the emitted signal strength from the system is lower. I think a great experiment would be with 2X hack RF modules communicating and measuring signal strength at different frequencies. Give it a try and let us know what you find out. As an RF guru in the drone World, I find this stuff very fun!
+HajoBenzin1 Yep, in some parts they talk about it as if Faraday cages blocked every kind of electromagnetic radiation by default, which is not true. Even in the actual Faraday cages meant for blocking radio signals you could see through them, i.e. doesn't block the visible spectrum.
+HajoBenzin1 A car is not a faraday cage. There are huge holes where any radio signal could get through: the windows, windshield, etc. Also the doors if, like alot of modern cars, the doors are made entirely of composite and not any metal at all.
A Faraday cage is not only about blocking radio signals, if a lightning strikes a car or a plane, you would be safe inside it, for example. Although a car would block radio if their wave length was roughly larger than that of the holes in it.
***** you'd be safe in a car because there is no conduction path, because the rubber tires are highly resistant. That doesn't make it a Faraday cage. That just makes makes it insulated.
hello, the grid is frequency selective. The hols work like radiating apertures. higher the frequency is greater is the leackage as you mentioned. I believe the shielding attenuation is around 35 to 40 dB at 2.4 GHz and this explains why you can still hear the microwaveoven even 20 m away on a special radio tuned to 2.4 GHz, or on a spectrum analyser.
actually, you had some variables you didnt account for... 1 : Cell Towers. The RF energy does not go from phone A - to Phone B directly, it goes through a tower first. so, this can be the difference at peoples houses, who may have lived different distances from different towers. and dont forget, there are 2 different links. 1 from the first cell to the tower 2 from the tower to the second cell no information or energy is transmitted between the 2 cell phones directly. 2 : line of sight. RF in this range is pretty much (but not totally) line of sight. so, if the door of the microwave is pointed toward a large open window it may have a better chance of working. if its pointed away, and its a small window, or, in a room in the middle of the house it may not work at all. Signals can bounce off of hard surfaces, but get less each time. think of going into a room with no lights. if the door is open, you can still see, but, its not as bright and this is coming from a tower blocks, or , miles away. cheers, Brad senior RF design engineer. Sprint PCS (retired)
None of you watched the full video or paid attention... She talks about variables not measured and interference not calculated... 😮 It is astonishing to me that all of the annoying comments correcting a woman in science come from men talking about things she actually spoke about in the video... However, I watch many other science videos with mens doing experiments or explaining things and comments are always of "how amazing the videos are", even when they clearly made a mistake and have to put a footnote on description (it's ok we are all humans), however, nobody even mentions... I wonder why 😅
Microwave ovens use "larger" forms of microwaves to cook food than the types of waves used by most cellphones. The Faraday Cage the surrounds the microwave's interior is designed to keep the microwaves inside the oven. But, if your phone uses the "smaller" waves by most phones they can pass into the microwave because the cage isn't usually designed to block them.
+Brian Straight if by "larger" you mean 2,450 mhz, instead of 2,400. That falls within the frequency range of wifi signals, which they mentioned several times in this video.
+Brian Straight That's not quite how that works.. for electromagnetic waves in free space, the wavelength is equal to the speed of light in free space divided by the frequency. That means that em waves with higher frequencies actually have a smaller wavelength than those with lower frequencies. Meaning that actually the Wi-Fi signal and microwaves are "smaller." Also I'm not going to go through the proof, but whether or not a wave can propagate through an opening depends on the wavelength, and not the amplitude. So saying "smaller" or "larger" is ambiguous, even when used correctly.
Try the dollar bill test. Put a dollar bill half way in and half out close the door see if you can pull it out. Move it around usually it is a place where the seal is not complete. As always fabulous explanations. Thank you.
Oh, the holes in this video, bigger than the holes in a farday cage; what you have made into a video is unnecessarily worrying... The distance between the tower and the microwave makes a difference, a big difference. The faraday cage would create loss in the signal path, if it is communicating with a nearby device or tower, there is more signal that can get in. Quick science & maths time: if my microwave puts out 60dBm (1000W), to get that down to 5mW (7dBm) I only need to loose 53dB, which is well within the -120dB sensitivity of a regular cellphone. WiFi is another example, my router puts out 20dBm, take away 53dBm equals -33dBm, which should be plenty enough to get through the microwave door (at close range).
Thank you so much for addressing this issue. This one has always made me wonder. That and the glue on cans when you use a can opener.. but that will be another day I hope to learn about.
robertdevald Well yes there is a window, look close and you will see a metal mesh in the window. To put it simple, if there wasn't any metal in the window the electromagnetic wave would go through with out any resistance. If there was a thick metal plate instead the resistance would be very high. The metal mesh forms a resistance to the electromagnetic wave, the resistance mainly depends on the size of the mesh and the wave length.
One important variable not accounted for is fading. RF signals that travel through the air experience significant reflections off the ground/houses/walls/people/furniture/etc. These reflections creating interference patterns as the reflected signals add and subtract and these patterns change dynamically as the "environment" that the signals travel through changes. The interference patterns are very small in scale, where moving the phone by a few inches in any direction can create massive changes of 20 dB (a factor of 100) or more in received signal strength. A person moving, or leaves rustling on the trees outside create dynamic changes to the environment. The implication is that whether a certain microwave allowed a call to ring or not could be simply dumb luck related to the dynamic environment of the RF signals travelling between the phone and tower. The "Faraday cage" of the microwave oven is by no means perfect. Since the metal if the microwave box is not a perfect electrical conductor, there will always be some signal leakage, but it does act as a very good attenuator of the signal (60-70+ dB). Depending on the signal strength available outside of the oven (which has to do with many factors including distance to the tower, presence of trees foliage, ground topography, building materials used in the house, the RF fading environment discussed above, and more) the signal strength inside the oven will be 60+ dB less. Whether the phone rings or not in a given environment is the result of all these complex signal strength factors. A better (but more complex/expensive) experiment would be to set up a signal source of a known strength inside of a microwave and then take measurements of the strength outside of the oven in a controlled environment such as an antenna range. You could also measure it versus frequency to see how it changes over common cellular frequencies.
+Physics Girl I love your videos. I have a degree in physics too (from the 70s). Here's an idea for one you could host. We all like our soda to stay fizzy once we've opened it and re-sealed it. We see tops for fizzy bottles with built in pumps in the stores that claim to keep the drink carbonated by pumping air into the bottle and pressurizing it. But they don't. The Partial Gas Law tells us that the presence of air (mostly Nitrogen and Oxygen) doesn't affect the pressure of CO2 at all no matter how much of it there is in the bottle. The CO2 ignores it completely. And the amount of CO2 in air is only 0.038% so pumping up these devices adds virtually no CO2 to your drink. And it's dissolved CO2 that makes your drink fizzy and nothing else. So the only way to fizz up your flat drink is to add CO2 directly with a Soda Stream machine, a bit of dry ice or... I don't know. Any ideas? I thought of submitting this idea to Mythbusters but haven't.
Charlie Franz Good point. I think the average layman assumes that the other compressed gases in the bottle will keep the CO2 dissolved because of the higher total pressure.
Very good video! i always knew this stuff. i climb cellular tower and install the cellular network and microwave dishes for towers. but finally somebody did a good video showing proof. which spectrum did you guys check? i saw 700. there is also 1900,850,2100 and 2600 usually for LTE. Thanks physics girl.
Some of your videos are just so good and different from other science channels. Like the supernova (I love this one) or strange water vortex. This one was very also interesting. Thank you.
Thanks for the fun, hands-on look at microwave radiation. The Faraday cage ‘thumb rule’ is not hard and fast. It’s much more complicated. The screens are much more like filters with attenuation of wave propagation than a gate that stops frequencies of smaller wavelength. The classical picture is the wave equation with modes, and the quantum picture includes electron-photon interactions.
OH GOD THIS EXPLAINS A LOT OMG. I used to work somewhere with a walk in freezer and if i had my phone in my pocket it would lose signal when i went in the freezer but come back when I came out. It also blocks wifi signal so if you were trying to get wifi and standing on the opposite side of the freezer from the router you couldn't get signal. Amazing!
Love your channel and all that you do. Thank you for your devotion towards spreading your joy of physics to everyone who will listen. I think you are great.
The first Faraday cage I built up (microwave) Did Not Leak RF radiation. I could not afford Samy Kamkars Faraday glove box 2-3000$ plus cost of Tap through inter face devices. You and Samy did a great job using test equipment, and multiple tests on different devices. The door is the weakest link on a fridge. If the door seal is ripped, or the latch is not tight the milk will spoil. Thanks for science and not opinion.
I recently found out on my WiFi network (I use commercial equipment at home (I work in networking) so it can see things that you usually can't like rogue APs, what channels are they interfering, their signal power, etc) that my electric smart meter is producing five distinct WiFi signals that are very strong. And when I say strong, they are in the -50dBM range at over 50 feet from my own access point (AP) (the smart meter is outside my house completeley opposed to where my AP is), 3 walls, 1 celling and many metal conducts and home appliances in between. I never saw those signals before and all of a sudden they are there. I also see (at -80dBm though) the same kind signals from one of the nearby house smartmeter too. So I pushed my investigation further because I didn't find it normal that my AP could catch signals that strong at that distance. I did the microwaves oven test like you did and what I found is getting me worried. I transformed by iPhone into a WiFi scanner (you can do that by using AirPort utilility and activating the Wi-Fi Scanner option) by using the Air Port utility and let it scan continuously. With that, you can now find the strenght of any wifi AP (up to 5Ghz) - and that is how I found out that it was my smartmeter that was emiting those signals. I put my iPhone in the microwaves oven while the scanner was On and it could "see" all wifi networks in the area, including mine, the smartmeter, my neigbors, etc. But when I closed the door of the microwaves oven, it lost all wifi signals - and my own AP was barely 20 feet away but still lost its signal - except those 5 smartmeter signals that barely lost their strenght : from -50 dBm to -60 dBm. Now I know I am writting this in 2022 and there was a lot of complains back in the 2010-era about the safety of these smartmeters, but working in networking and knowing a bit about signal strenght for network optimization - and also what they can do the more you are near an AP - I can testify that these are not healthy level of radiations that are emitted from that smartmeter that far away. The room in my house that is adjacent to the wall where the smartmeter is installed outside receives signal strenght of -30 to -40dBm - that's the same as being 10 feet from your own AP at home in straight line with no obstable in between. I don't have my mG reader with me, but I will and measure those signal to see how "cooked" we are getting each day.
A large part of why your phone will ring in some ovens vs others is due to your location. If you are near a cell site, you have a stronger signal so the attenuation of the oven cavity isolation isn't enough to prevent communications. This is likely why you got a Ring with the WiFi calling even though it is at the frequency that the oven cavity is supposed to block, the WiFi signal level was much higher where the oven was located. I did some testing with my oven and I found that I get about -42db attenuation into the cavity with the door closed at WiFi channel 6. Remember that no shielding of anything is 100% and 40 db is a ton of isolation. Yes ALL microwaves will leak!! In the case of my oven, if you assume 700 watts of RF in the cavity and -42db isolation that means that ~44mw are leaking. That is about 1/4 of the RF power from your cell phone that you hold to your head!! And with RF remember that the field strength is reduced with the square of the distance. Even if you hold your head against your microwave, you receive far less RF radiation then from your phone. Funny how us humans fear things irrationally yet hold no concern for something like our phone which exposes us to much more radiation...
Very nice, and I think you got to one of the issues at the very end. the space between The grid matters. We are not dealing with inductive electric currents, we are dealing with electromagnetic radiation. The ratio of the grid openings and the frequency of the microwave radiation matters. Certain fractions of the frequency will block, and other fractions will allow passage. So you can have frequencies very close to the blocked frequency getting through.
Also, your phone might be on different network frequencies in different locations. Since phones operate on frequencies ranging from 800Mhz to 2500Mhz, your shielding may not have been ideal.
Thank you Physics Girl :) My suggestion, if nobody else has done so: Measure the leaked 2.45GHz radiation off your microwave oven(s), using Samy's device, as a function of perpendicular distance r from the oven's door screen. The amplitude of the leaked radiation should drop down as 1/r2, and does so very quickly, because of refraction - its wavelength is about 12cm, while the screen's holes' diameter is on the order of 3mm. Then the leakage is so little just, say, r=1cm outside of the oven's screen, that you can put your hand there while using the oven, and wouldn't feel a thing. It'd be cool to see the measurement data, though.
Did you heard about "slot antenna"? It is just cut in metal sheet, whith some feed point near. So, microwave oven has door, which is practically the same slot if there are no additional metal contacts or some absorbing elements on the door.
Physics Girl, you should look into wave guides and the size of the opening to let a freq through. Before I saw the video, I guessed that the phone would still operate in the microwave as you discoveted. The reason for my hypothesis was the theory behind wave guides and the size of the openings of the "mesh" on the microwave door.
You have made your conclusion based on only one microwave. My question have you tried the same setup for the rest of the microwaves you used in the beginning of the show? I liked the video a lot where I watched it twice and that is the question that came to my mind Thank you
I know that there are resonant lengths for antennas at which they are most efficient. For example, a 1/4 wavelength antenna is more efficient than a slightly longer one, but a full wavelength antenna is even more efficient. Can Faraday cages have these same sort of "nodes" around which signals can pass through? I would expect that, even though a small amount of leakage occurred, the attenuation would be far too great for the 2.4 Ghz Wi-Fi signal to get through unless there was something else going on. The FCC maximum allowed transmit power for 2.4 Ghz Wi-Fi is 1 watt but it's not uncommon for microwaves to radiate 500-1,000 watts. You didn't give the power level detected, but it looked to be faint at whatever scale you were measuring.
I am surprised. I thought microwave ovens would be much better Faraday cages than they actually turned out to be.
+Physics Videos by Eugene Khutoryansky
Actually the RF seal on a microwave is tuned to the magnetron's frequency(2.4 GHz) to reflect that frequency back to the inside of the box instead of shorting it out. It's a common technique used in radar transmitters.
It is very hard to stop microwaves from leaking through the door seals. 2.4GHz is almost like water. It leaks everywhere. The gap in the door is considerably smaller at 700 mhz than at 2.4ghz, so the seals work better at lower frequencies. Also, the transmitter for the wifi is only a few feet away. The transmitter for the cellular is miles away. The signal strengths are vastly different.
another thing is that microwaves just stop a lot of the power of the signal. that is what cooks the food. the power not the frequency. im actually surprised that the phone didnt work in all of them.
actually that makes sense why it worked in some but not others since when they were further from a cell tower or wifi router the power of the signal would be lessened thus allowing the microwave to stop it verses when you are closer it cant stop it as much.
How clean were the door seals?
Great, my friend watched this video with me and all she took from it is that the microwave leaks radiation.
She completely ignored where you said it was non ionizing and is currently trying to cover the microwave with "protective foil"
Thanx Diana.
I guess the good news is, after she's done entombing the microwave, she won't have enough tin foil left to make a hat.
+Diana, the Inorganic Vegan well you see it as light and feel it as heat
+daniel117100
I know. I'm just explaining the mentality of most laymen.
+Chad C. Have you seen about bananas? They are radioative, and the ionizing type too!
ShapeDoppelganger
Although not enough radiation to harm you*
lol
Now try a banana and travel through time
For those of you who are wondering what this comment is about. It actually refers to an anime called "SteinsGate", in which a microwave acts as time-machine
+Adarsh VA Haha, I love that anime.
El Psy Congroo
Tootooroo!
I was looking for this comment
revisiting this months later, this is the coolest video.
I remember dragging an HP spectrum analyzer home from work back in the 80's to do this. Most of the leakage was at the door joint. Holding the door tighter there was less leakage so I adjusted it. The internet was a university novelty then, mobile phones were mounted in the trunks of doctors and lawyers and everything over 1 GHz was a small fortune.
Nice work! I really liked the RF investigation. Nice shirt too ;)
+Applied Science Yeah, I thought I’d seen that logo somewhere.
Saw shirt and scrolled down hoping to see this comment. You never disappoint, Ben...
I’m wondering how much the H-Field might play a role here.
A Faraday cage, like a microwave oven, is more effective at blocking the electrical component of the electromagnetic radiation. But the magnetic component usually goes straight through the shielding unaffected.
Damn, I was looking for 'Psychic Girl'...this is better anyways
troll
+thedoctorzeus Psychic Girl never looks for you,for she always knows where you are.
Yeah i love physics girl
I can see the classic "Art of Electronics" book in the background
I love this video!
What are you doing here :l
@@Aj3.14 why must every comment by a science RUclipsr include a reply by somebody who's shocked that similar people watch each other's videos?
If anything, I find it interesting that James used his Shorts account to browse, rather than the original one or something more incognito.
(More seriously, that emoji seems to imply you're disappointed. That's even more strange than being surprised by somebody famous.)
great video!! shared many times on facebook!! well done!
Shoutout for Samy's _Applied Science_ T-shirt! That's how you know he's a cool dude!
Years ago, I powered up a radar detector with a power adapter and tested to see if it would pick up a signal from the microwave. It did. It showed up as X band, which was around 10 GHz.
With the wifi call, are your sure that the wifi was on 2.4GHz and not 5GHz? The latter is becoming more popular in a bid to find more spectrum.
+Jonathan Sawyer yes. Samy had two networks, we checked to make sure I was on the 2.4GHz network. Thanks for the question!
The subsequent question is how well would the microwave work as a faraday cage at 5GHz?
+Jonathan Sawyer if the 2.4 can enter the 5 probably can.
H I think you are probably right but if the microwave did act as a faraday cage at 700MHz anything is possible. Although the wavelength is considerably shorter at 5GHz.... I'm rambling now. I'll stick to playing at 7MHz.
+Physics Girl Have you checked the smartphone was still on the 2.'4GHz network AFTER removing it from Samy's microwave? Because it could have quickly switched to 5GHz as the 2.4GHz faded away.
What I appreciate most in the video is the the final discussion about bias in the observation and the sample was not homogeneous in the other characteristics :)
i tried calling my cellphone when he was inside the microwave , i didn't get the call and the Wi-Fi was blocked , my microwave is very safe😂
however, there are also 5Ghz wifi antennas which can send the signal through smaller holes... keep an eye on those...
That doesn't necessarily follow.
That settles it. You are cooking 😋
I also did that...now my foun doesnt want to connect to wifi...what must i do please help..i even regret.my foun is Samsung j4 core
@@cezarcatalin1406 well it doesnt matter if the call signals get in as long as microwaves dontget out.
I really like the way you're approaching the problem. Feels really well structured and eleborated.
Yeahhh Samy !!! that guy is incredible. Btw the art of electronics spotted ;)
As an avionics technician, I have performed leak tests on microwave ovens installed on aircraft. When I was performing these tests in the late 80's, EVERY microwave I tested leaked beyond acceptable limits. I was actually surprised to see microwaves that did not leak.
Wait... logo from Applied Science channel ?
Yes! He's selling shirts now!
+Roshkin Ok, nice to know ;)
Yeah, Applied Science is amazing. I'm still waiting on the gecko tape. He's incredible to watch.
+Physics Girl Note that Wi-Fi also uses the 5GHz band. If his wireless router supports it, the facetime call could have used 5GHz, not 2.4GHz thereby penetrating the microwave.
By pure coincindence, this video came out when I was watching Stein Gate.
Same Here I Searched.
Microwave, Cellphone, SERN.
Interesting to see those experiments really done. Thanks!
The reason WiFi was getting through better than cellphone signals could be that the cell tower was a lot farther away than the WiFi access point. Even though cellphone towers emit more power and have better high-gain antennas (they radiate most energy horizontally and only a little bit upwards -> poor reception in airplanes), the inverse-square law means the it is likely that a lot less less cellphone tower field intensity was arriving than WiFi field intensity.
2:11 An applied science shirt, nice to see that around :D
This video is so great. You started with a solid science concept and really followed it where it took you. Thanks for creating.
+YouCanScienceIt But, as she stated herself, she ignored too many variables to make it a good research. It makes nice watching, but the research was crap, haha. Fortunately she says it herself too.
You get a thumbs up coz the guy is wearing an Applied Science t-shirt at 2:20 ... :D
instructions not clear, my phone turned into green slime
Good job pointing out the confounding variables.
+Rob Kinney I also liked that part, it was vaguely reminiscent of the summary in an actual scientific paper..
It's possible your iPhone used the 5 GHz wifi signals when it was in the microwave. That would explain why it still received the call when the microwave was (supposedly) blocking the 2.4 GHz signal. Also, thumbs up for the Applied Science t-shirt! :)
*accidentally create a time machine
El psy kangaroo
Steins; Gate
El psy congroooooo
Physics Girl, you have been stepping up your game. Bravo!
Stein; gate, anyone?
I'm glad you mentioned the position, orientation and distance away of the microwave from a cellphone tower, because it makes a huge difference. Cellphones can tolerate variations in received signal power of around 60dB which is a factor of one million. So an oven allowing a millionth of the signal in from a really close tower might be the same as no Faraday cage at all if the tower is at extreme range. Still it's mlldly worrying that any measurable amount of 2.4GHz energy escapes. Thanks, I enjoyed it. Bill Dixon
Samy Kamkar AND Physics Girl !!!
I'm having a ScienceGasm
SAMY!!!! love his work.
Samy is my hero
I actually work in the industry and we use microwave ovens for testing. It used to be that you could unscrew the antenna and put in a coax cable to connect to the cell hardware but external antennas disappeared. Note that in the US voice calls would use CDMA band classes 1 and 2 at 850 MHz and 1900 MHz (PCS) and sometimes the auxiliary 800MHz range. But for testing LTE data which runs in the GHz bandclasses we place the mobile UE in the microwave and run an antenna wire inside from the eNodeB. This prevents the UE from attaching to a commercial signal and our testing from affecting any users of the commercial signal. We are not allowed to bleed any RF.
Another interesting fact is that some high efficiency energy saving windows are very good at blocking LTE radio ranges. So much so that I have seen a demonstration where a mobile was placed less that two feet from from the eNodeB antenna and one of those salesman demonstration mini windows placed between them. The mobile lost communication immediately. So if you are getting a bad signal inside the house doing the "natural" thing of going to the window could be the worst choice to make.
Lead and other metals in glass and tint would be the likely culprits. Security mesh and heating elements may compound that.
The average residential wall should generally block less RF than a typical window.
Where I work the mess hall (the only place we're generally supposed to use personal phones) has a decorative aluminum grid overhead to diffuse lights and act as a ceiling, somewhat hiding ducts and whatnot. Have to go into another room (which is full of windows, lol) or outside to get useful call reception. e.e (It's a "clean" factory, so we don't just walk outside.)
This video was unsponsored by carcassonne :) The blur snub of an awesome game!
Thanks for the information. I have read to put one's emergency radio and electronic equipment in an old microwave oven with the cord cut to protect against an EMP, and told to test it in a similar manner with the FM radio band on. Now, I have my doubts. Your test is good for people as a cheap way to check their microwave oven. Thanks. Good luck with your site.
U should turn on the microwave
Ben bruh iz mi speeling 2 guud four u
That would be wasting phones.
+Ben
Yew
Huh. Didn't know that.
+Animatotron Instructions unclear; burnt house down
Samy & Dianna, best team ever. I love Samy's channel for all of his infosec, and Dianna's for science. Surprise surprise to see them both. Also way to represent the hackrf! Great video.
The issue may not be between microwaves, it may be the signal strength of the surrounding cell phone towers that your phone is communicating with. To be sure you should gather the different microwaves in the same place, and see if the results are the same.
Thank you humble man for the men-explaining. Science Girl literally said that variables such as placement of microwaves, age, cellphone towers nearby, and etc could have affected the experience... We, the people of science, all know it was just a simple demonstration, not study for a publication... I wonder if was a man you would come here and bluntly correct the demonstration and ignore the fact that the possible interference of unknown variables have been mentioned 😒🤡
I ALREADY LOVE THIS CHANNEL SCIENCE!!!!!!!!
Oh, so you love microwaves too ♥
I know this won't get answered but I like it when you and veritasuim combined shows y'all 2 could put your minds together and be awsome
One thought: if you considered the microwave oven as an attenuator rather than a perfect cage, you would definitely see a different picture. Your WiFi network is much closer in proximity than the nearest cellular tower and thus your reduction in signal strength might be the same, but still have enough to make it through eventhough the emitted signal strength from the system is lower.
I think a great experiment would be with 2X hack RF modules communicating and measuring signal strength at different frequencies. Give it a try and let us know what you find out. As an RF guru in the drone World, I find this stuff very fun!
Video Aerial Systems
What an awesome video! I always wanted to visualize EMR and you delivered. Nice!
Thank you physic girl!
(That's the closest I'll ever get to thanking a super heroine)
I loved the progression of this video, great job all!
The title of the video was very hard for me to read for some reason
did call and cell mess you up?
+Barrett Coleman Yap
+jesse ding
"Can you call a mobile phone in the microwave?"
Better?
Really cool. Love the conclusions at the end of the experiment.
a car is also a faraday cage, but you can call a cell phone in it :))
+HajoBenzin1 Yep, in some parts they talk about it as if Faraday cages blocked every kind of electromagnetic radiation by default, which is not true. Even in the actual Faraday cages meant for blocking radio signals you could see through them, i.e. doesn't block the visible spectrum.
+T Trindad no, they expressly defined that they were talking about the microwave range, between 1mhz and 6ghz, several times during the video.
+HajoBenzin1 A car is not a faraday cage. There are huge holes where any radio signal could get through: the windows, windshield, etc. Also the doors if, like alot of modern cars, the doors are made entirely of composite and not any metal at all.
A Faraday cage is not only about blocking radio signals, if a lightning strikes a car or a plane, you would be safe inside it, for example. Although a car would block radio if their wave length was roughly larger than that of the holes in it.
***** you'd be safe in a car because there is no conduction path, because the rubber tires are highly resistant. That doesn't make it a Faraday cage. That just makes makes it insulated.
I was just about to test this but my phone was dead.... so I searched YT and got you. SAMMY KAMKAR IS IN THE HOUSE! He's my hero!
You have a ton of friends with microwaves? I'm jealous.
+GelberFisch8 Do you not have friends or just all of your friends don't have microwaves?
+SergeofBIBEK take a wild guess :(
I have very few friends, but all of them have microwaves. I could never be friends with someone without a microwave.
hello, the grid is frequency selective. The hols work like radiating apertures. higher the frequency is greater is the leackage as you mentioned. I believe the shielding attenuation is around 35 to 40 dB at 2.4 GHz and this explains why you can still hear the microwaveoven even 20 m away on a special radio tuned to 2.4 GHz, or on a spectrum analyser.
actually, you had some variables you didnt account for...
1 : Cell Towers.
The RF energy does not go from phone A - to Phone B directly, it goes through a tower first.
so, this can be the difference at peoples houses, who may have lived different distances from different towers.
and dont forget, there are 2 different links.
1 from the first cell to the tower
2 from the tower to the second cell
no information or energy is transmitted between the 2 cell phones directly.
2 : line of sight.
RF in this range is pretty much (but not totally) line of sight.
so, if the door of the microwave is pointed toward a large open window
it may have a better chance of working.
if its pointed away, and its a small window, or, in a room in the middle of the house
it may not work at all.
Signals can bounce off of hard surfaces, but get less each time.
think of going into a room with no lights.
if the door is open, you can still see, but, its not as bright
and this is coming from a tower blocks, or , miles away.
cheers,
Brad
senior RF design engineer.
Sprint PCS (retired)
So, anyways, if she is right, then Snowden did not know what he was talking about.
The door of the microwave has metal mesh in it.
None of you watched the full video or paid attention... She talks about variables not measured and interference not calculated... 😮 It is astonishing to me that all of the annoying comments correcting a woman in science come from men talking about things she actually spoke about in the video... However, I watch many other science videos with mens doing experiments or explaining things and comments are always of "how amazing the videos are", even when they clearly made a mistake and have to put a footnote on description (it's ok we are all humans), however, nobody even mentions... I wonder why 😅
awesome. great breakdown of the experiment at the end. physics work. loved it
Microwave ovens use "larger" forms of microwaves to cook food than the types of waves used by most cellphones. The Faraday Cage the surrounds the microwave's interior is designed to keep the microwaves inside the oven. But, if your phone uses the "smaller" waves by most phones they can pass into the microwave because the cage isn't usually designed to block them.
+Brian Straight Finally someone who is not an idiot.
***** and the video is wrong
+Dave Carsley no, the video is right. The vast majority of commercial microwaves use a frequency of 2,450 mhz.
+Brian Straight if by "larger" you mean 2,450 mhz, instead of 2,400. That falls within the frequency range of wifi signals, which they mentioned several times in this video.
+Brian Straight That's not quite how that works.. for electromagnetic waves in free space, the wavelength is equal to the speed of light in free space divided by the frequency. That means that em waves with higher frequencies actually have a smaller wavelength than those with lower frequencies. Meaning that actually the Wi-Fi signal and microwaves are "smaller." Also I'm not going to go through the proof, but whether or not a wave can propagate through an opening depends on the wavelength, and not the amplitude. So saying "smaller" or "larger" is ambiguous, even when used correctly.
Try the dollar bill test. Put a dollar bill half way in and half out close the door see if you can pull it out. Move it around usually it is a place where the seal is not complete. As always fabulous explanations. Thank you.
Oh, the holes in this video, bigger than the holes in a farday cage; what you have made into a video is unnecessarily worrying...
The distance between the tower and the microwave makes a difference, a big difference. The faraday cage would create loss in the signal path, if it is communicating with a nearby device or tower, there is more signal that can get in.
Quick science & maths time: if my microwave puts out 60dBm (1000W), to get that down to 5mW (7dBm) I only need to loose 53dB, which is well within the -120dB sensitivity of a regular cellphone. WiFi is another example, my router puts out 20dBm, take away 53dBm equals -33dBm, which should be plenty enough to get through the microwave door (at close range).
Bro this is a "physics" video aimed at the people who are: non believers in evolution, gravity, actual science. Pretty much Trump supporters.
+VideoInked and if unnecessarily alarmist
Thank you so much for addressing this issue.
This one has always made me wonder. That and the glue on cans when you use a can opener.. but that will be another day I hope to learn about.
That Faraday cage explanation was bogus. A car is a Faraday cage too, yet you can still place calls while you're in a car. -__-
windows
TheRestOfTheWeek Your microwave doesn't have a window? What?
robertdevald Well yes there is a window, look close and you will see a metal mesh in the window.
To put it simple, if there wasn't any metal in the window the electromagnetic wave would go through with out any resistance. If there was a thick metal plate instead the resistance would be very high. The metal mesh forms a resistance to the electromagnetic wave, the resistance mainly depends on the size of the mesh and the wave length.
TheRestOfTheWeek Okay, good to know.
Perhaps the size of the holes in the mesh influenced the test in the video.
robertdevald I think the design of the door has a big influence, how well the door closes.
Excelent the presentation and the use of the scientific method. Keep the good work.
Your video is awesome but the title isn't quite appealing.
What would you have titled it instead?
+Physics Girl "She puts her cell phone in the microwave. When I saw what happened next, I lost it!"
+Physics Girl "Can you send nude selfies to a cell phone in the microwave?"
+Physics Girl "Microwaves don't block cell phone signals because... Obama and stuff."
+Physics Girl I'm out of ideas. :(
Heyyy its Samy. I followed your work for years. you're awesome dude.
One important variable not accounted for is fading. RF signals that travel through the air experience significant reflections off the ground/houses/walls/people/furniture/etc. These reflections creating interference patterns as the reflected signals add and subtract and these patterns change dynamically as the "environment" that the signals travel through changes. The interference patterns are very small in scale, where moving the phone by a few inches in any direction can create massive changes of 20 dB (a factor of 100) or more in received signal strength. A person moving, or leaves rustling on the trees outside create dynamic changes to the environment.
The implication is that whether a certain microwave allowed a call to ring or not could be simply dumb luck related to the dynamic environment of the RF signals travelling between the phone and tower.
The "Faraday cage" of the microwave oven is by no means perfect. Since the metal if the microwave box is not a perfect electrical conductor, there will always be some signal leakage, but it does act as a very good attenuator of the signal (60-70+ dB). Depending on the signal strength available outside of the oven (which has to do with many factors including distance to the tower, presence of trees foliage, ground topography, building materials used in the house, the RF fading environment discussed above, and more) the signal strength inside the oven will be 60+ dB less. Whether the phone rings or not in a given environment is the result of all these complex signal strength factors.
A better (but more complex/expensive) experiment would be to set up a signal source of a known strength inside of a microwave and then take measurements of the strength outside of the oven in a controlled environment such as an antenna range. You could also measure it versus frequency to see how it changes over common cellular frequencies.
Amazing! I could tell where this was going from the beginning. Great info!
+Physics Girl I love your videos. I have a degree in physics too (from the 70s). Here's an idea for one you could host.
We all like our soda to stay fizzy once we've opened it and re-sealed it. We see tops for fizzy bottles with built in pumps in the stores that claim to keep the drink carbonated by pumping air into the bottle and pressurizing it. But they don't. The Partial Gas Law tells us that the presence of air (mostly Nitrogen and Oxygen) doesn't affect the pressure of CO2 at all no matter how much of it there is in the bottle. The CO2 ignores it completely. And the amount of CO2 in air is only 0.038% so pumping up these devices adds virtually no CO2 to your drink. And it's dissolved CO2 that makes your drink fizzy and nothing else.
So the only way to fizz up your flat drink is to add CO2 directly with a Soda Stream machine, a bit of dry ice or... I don't know. Any ideas?
I thought of submitting this idea to Mythbusters but haven't.
+Warren NZ Indeed. Pressure and solubility are independent of each other.
Charlie Franz Good point. I think the average layman assumes that the other compressed gases in the bottle will keep the CO2 dissolved because of the higher total pressure.
Very good video! i always knew this stuff. i climb cellular tower and install the cellular network and microwave dishes for towers. but finally somebody did a good video showing proof. which spectrum did you guys check? i saw 700. there is also 1900,850,2100 and 2600 usually for LTE. Thanks physics girl.
6:56 the two blurred boxes unblurred
Cool video, but when I saw the title I was expecting more of trying to call it as your microwave your phone. Now that would be awesome.
+Matthew Purcell It just kills your phone. So, no awesomeness. :-)
Some of your videos are just so good and different from other science channels. Like the supernova (I love this one) or strange water vortex. This one was very also interesting. Thank you.
Nice video, loved your guests applied science tshirt. Another outstanding youtuber.
Beautiful Dianna :) I liked the way yoy went through what you were thinking at each point
Thanks for the fun, hands-on look at microwave radiation.
The Faraday cage ‘thumb rule’ is not hard and fast. It’s much more complicated. The screens are much more like filters with attenuation of wave propagation than a gate that stops frequencies of smaller wavelength. The classical picture is the wave equation with modes, and the quantum picture includes electron-photon interactions.
Cool video, the only thing that's missing is turning the microwave on! :)
Interesting experiment, thanks for sharing!
such an awesome show.....you are the best, Physics Girl
OH GOD THIS EXPLAINS A LOT OMG. I used to work somewhere with a walk in freezer and if i had my phone in my pocket it would lose signal when i went in the freezer but come back when I came out. It also blocks wifi signal so if you were trying to get wifi and standing on the opposite side of the freezer from the router you couldn't get signal. Amazing!
This is good, a proper experiment that left me wondering about the results.
thank you for making physics cooler !!
Love your channel and all that you do. Thank you for your devotion towards spreading your joy of physics to everyone who will listen. I think you are great.
Electronic engineering rocks, it's my profession. 23 years telecom. We used to just build leak detectors checking the door seals. Good job.
I love this channel. Thank you.
Fantastic dear.....physics is really awesome
I thought it was the amplitude of the waves that determined whether or not they got through, not the wavelength. I learned something new today!
The first Faraday cage I built up (microwave) Did Not Leak RF radiation. I could not afford Samy Kamkars Faraday glove box 2-3000$ plus cost of Tap through inter face devices. You and Samy did a great job using test equipment, and multiple tests on different devices. The door is the weakest link on a fridge. If the door seal is ripped, or the latch is not tight the milk will spoil. Thanks for science and not opinion.
I recently found out on my WiFi network (I use commercial equipment at home (I work in networking) so it can see things that you usually can't like rogue APs, what channels are they interfering, their signal power, etc) that my electric smart meter is producing five distinct WiFi signals that are very strong. And when I say strong, they are in the -50dBM range at over 50 feet from my own access point (AP) (the smart meter is outside my house completeley opposed to where my AP is), 3 walls, 1 celling and many metal conducts and home appliances in between. I never saw those signals before and all of a sudden they are there. I also see (at -80dBm though) the same kind signals from one of the nearby house smartmeter too.
So I pushed my investigation further because I didn't find it normal that my AP could catch signals that strong at that distance. I did the microwaves oven test like you did and what I found is getting me worried. I transformed by iPhone into a WiFi scanner (you can do that by using AirPort utilility and activating the Wi-Fi Scanner option) by using the Air Port utility and let it scan continuously. With that, you can now find the strenght of any wifi AP (up to 5Ghz) - and that is how I found out that it was my smartmeter that was emiting those signals.
I put my iPhone in the microwaves oven while the scanner was On and it could "see" all wifi networks in the area, including mine, the smartmeter, my neigbors, etc. But when I closed the door of the microwaves oven, it lost all wifi signals - and my own AP was barely 20 feet away but still lost its signal - except those 5 smartmeter signals that barely lost their strenght : from -50 dBm to -60 dBm.
Now I know I am writting this in 2022 and there was a lot of complains back in the 2010-era about the safety of these smartmeters, but working in networking and knowing a bit about signal strenght for network optimization - and also what they can do the more you are near an AP - I can testify that these are not healthy level of radiations that are emitted from that smartmeter that far away. The room in my house that is adjacent to the wall where the smartmeter is installed outside receives signal strenght of -30 to -40dBm - that's the same as being 10 feet from your own AP at home in straight line with no obstable in between. I don't have my mG reader with me, but I will and measure those signal to see how "cooked" we are getting each day.
Loved this episode!
Your channel continues to fascinate me!
Thank you so much! :)
awesome you met this guy. Samy is my hero!
Wow, this was very interesting experiment! Keep it up, cause that's what I like about science.
A large part of why your phone will ring in some ovens vs others is due to your location. If you are near a cell site, you have a stronger signal so the attenuation of the oven cavity isolation isn't enough to prevent communications. This is likely why you got a Ring with the WiFi calling even though it is at the frequency that the oven cavity is supposed to block, the WiFi signal level was much higher where the oven was located.
I did some testing with my oven and I found that I get about -42db attenuation into the cavity with the door closed at WiFi channel 6. Remember that no shielding of anything is 100% and 40 db is a ton of isolation.
Yes ALL microwaves will leak!! In the case of my oven, if you assume 700 watts of RF in the cavity and -42db isolation that means that ~44mw are leaking. That is about 1/4 of the RF power from your cell phone that you hold to your head!! And with RF remember that the field strength is reduced with the square of the distance. Even if you hold your head against your microwave, you receive far less RF radiation then from your phone. Funny how us humans fear things irrationally yet hold no concern for something like our phone which exposes us to much more radiation...
I love your curiosity will be back to watch more later
Very nice, and I think you got to one of the issues at the very end. the space between The grid matters. We are not dealing with inductive electric currents, we are dealing with electromagnetic radiation. The ratio of the grid openings and the frequency of the microwave radiation matters. Certain fractions of the frequency will block, and other fractions will allow passage. So you can have frequencies very close to the blocked frequency getting through.
This video was awesome! It's one of the best modern examples of the so-called scientific spirit! Great job there!
Also, your phone might be on different network frequencies in different locations. Since phones operate on frequencies ranging from 800Mhz to 2500Mhz, your shielding may not have been ideal.
Thank you Physics Girl :)
My suggestion, if nobody else has done so: Measure the leaked 2.45GHz radiation off your microwave oven(s), using Samy's device, as a function of perpendicular distance r from the oven's door screen.
The amplitude of the leaked radiation should drop down as 1/r2, and does so very quickly, because of refraction - its wavelength is about 12cm, while the screen's holes' diameter is on the order of 3mm. Then the leakage is so little just, say, r=1cm outside of the oven's screen, that you can put your hand there while using the oven, and wouldn't feel a thing. It'd be cool to see the measurement data, though.
Did you heard about "slot antenna"? It is just cut in metal sheet, whith some feed point near. So, microwave oven has door, which is practically the same slot if there are no additional metal contacts or some absorbing elements on the door.
Physics Girl, you should look into wave guides and the size of the opening to let a freq through. Before I saw the video, I guessed that the phone would still operate in the microwave as you discoveted. The reason for my hypothesis was the theory behind wave guides and the size of the openings of the "mesh" on the microwave door.
You have made your conclusion based on only one microwave.
My question have you tried the same setup for the rest of the microwaves you used in the beginning of the show?
I liked the video a lot where I watched it twice and that is the question that came to my mind
Thank you
I know that there are resonant lengths for antennas at which they are most efficient. For example, a 1/4 wavelength antenna is more efficient than a slightly longer one, but a full wavelength antenna is even more efficient. Can Faraday cages have these same sort of "nodes" around which signals can pass through? I would expect that, even though a small amount of leakage occurred, the attenuation would be far too great for the 2.4 Ghz Wi-Fi signal to get through unless there was something else going on. The FCC maximum allowed transmit power for 2.4 Ghz Wi-Fi is 1 watt but it's not uncommon for microwaves to radiate 500-1,000 watts. You didn't give the power level detected, but it looked to be faint at whatever scale you were measuring.