Faraday Cage Physics EXPLAINED using 1843 Ice Pail Experiment and History
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Date: 2022-12-27
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Comments and reviews: 20
This
FWIW, an empirical single data point:
Several decades ago (when cellphones used analog FM, I placed a cellphone inside a Halliburton aluminum camera case. The camera case was on the living room carpeted floor. Needless to say, the case was floating _way_ above electrical ground.
I called the phone from my landline. The phone rang.
Conjecture: The pot in the video seems to be sitting on a stainless steel range or counter top. I surmised that either it is grounded, or, it has enough conductive mass to serve as a virtual ground for purposes of sinking RF intercepted by the pot and foil.
For those pocket Faraday cage bags for containing cellphones, assuming that they function as-billed, I would suspect that the human body is sinking the RF picked up by the bag. The close proximity would obviate any need for direct physical contact.
As an aside, lightning rods do NOT conduct lightning strikes to ground. Their role is that of a lightning _preventer, _ which they perform by bleeding the ambient electrical charge to ground.
IMO an ungrounded Faraday cage is conceptually identical to an ungrounded lightning rod, and would perform just as well.
And while something as weak as a few microvolts of RF can be sunk by something smaller than a planetary ground, I suppose the same could be said for a lightning rod that fed into something impressively massive, yet smaller than the planet.
And as I sometimes used to see on Usenet before most of the lurkers here were born, No flames, please!
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FWIW, an empirical single data point:
Several decades ago (when cellphones used analog FM, I placed a cellphone inside a Halliburton aluminum camera case. The camera case was on the living room carpeted floor. Needless to say, the case was floating _way_ above electrical ground.
I called the phone from my landline. The phone rang.
Conjecture: The pot in the video seems to be sitting on a stainless steel range or counter top. I surmised that either it is grounded, or, it has enough conductive mass to serve as a virtual ground for purposes of sinking RF intercepted by the pot and foil.
For those pocket Faraday cage bags for containing cellphones, assuming that they function as-billed, I would suspect that the human body is sinking the RF picked up by the bag. The close proximity would obviate any need for direct physical contact.
As an aside, lightning rods do NOT conduct lightning strikes to ground. Their role is that of a lightning _preventer, _ which they perform by bleeding the ambient electrical charge to ground.
IMO an ungrounded Faraday cage is conceptually identical to an ungrounded lightning rod, and would perform just as well.
And while something as weak as a few microvolts of RF can be sunk by something smaller than a planetary ground, I suppose the same could be said for a lightning rod that fed into something impressively massive, yet smaller than the planet.
And as I sometimes used to see on Usenet before most of the lurkers here were born, No flames, please!
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Khalif
Can ya expand Faraday Cage doesn't work against the magnet, and anything, doesn't block the light, well, it is because of the metal itself is not high enough of magnet mass to create a light blocking, so in connecting light blocking is linked to magnet blocking since the light and magnet link together which light has high speed to create light and magnet has high speed within mass and the mass has high charges to cause reactions to outside, so the power of metal is low enough so the magnet and light work, so you can see and you can use the compass. So, it is depended on how much of a conductor of a mass, if it is so high so another conductor effect will be so low, from the external conductor to the internal conductor. Can upgrade the book so can increase or decrease the conductor or create a mass that causes the conductor or inductor to be high or low if ya can understand the process. Glass is a high inductor and metal is the high conductor. So, the conductor can be higher than the inductor and the inductor can be higher than conductor. . What happens if you are under the higher conductor of mass what kind of effect on you have? With the hole that you are under a higher conductor, so higher level than metal.
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Can ya expand Faraday Cage doesn't work against the magnet, and anything, doesn't block the light, well, it is because of the metal itself is not high enough of magnet mass to create a light blocking, so in connecting light blocking is linked to magnet blocking since the light and magnet link together which light has high speed to create light and magnet has high speed within mass and the mass has high charges to cause reactions to outside, so the power of metal is low enough so the magnet and light work, so you can see and you can use the compass. So, it is depended on how much of a conductor of a mass, if it is so high so another conductor effect will be so low, from the external conductor to the internal conductor. Can upgrade the book so can increase or decrease the conductor or create a mass that causes the conductor or inductor to be high or low if ya can understand the process. Glass is a high inductor and metal is the high conductor. So, the conductor can be higher than the inductor and the inductor can be higher than conductor. . What happens if you are under the higher conductor of mass what kind of effect on you have? With the hole that you are under a higher conductor, so higher level than metal.
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Cool
Kathy Loves Physics & History Thanks for the Faraday cage video: ) I have a question that I have been trying to clarify for some years: We are are group of scuba divers, and we are trying to understand the potential dangers of diving during a thunderstorm. Does your understanding of the physics involved bring you a clear answer on this question?
I must confess, I've been underwater several times while the lightning flashed. Never had any problems, but we've been wondering if we should stop that! xD
btw, we found ourselves in those situations by jumping into the water during a bright sunny day, and after a couple of hours under water, the weather had shifted and the thunderstorms moved in. We haven't yet jumped into the water >during< a thunderstorm! xD Best to err on the side of caution, still It would be very interesting to understand the physics and potential dangers better.
Thanks Kathy: )
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Kathy Loves Physics & History Thanks for the Faraday cage video: ) I have a question that I have been trying to clarify for some years: We are are group of scuba divers, and we are trying to understand the potential dangers of diving during a thunderstorm. Does your understanding of the physics involved bring you a clear answer on this question?
I must confess, I've been underwater several times while the lightning flashed. Never had any problems, but we've been wondering if we should stop that! xD
btw, we found ourselves in those situations by jumping into the water during a bright sunny day, and after a couple of hours under water, the weather had shifted and the thunderstorms moved in. We haven't yet jumped into the water >during< a thunderstorm! xD Best to err on the side of caution, still It would be very interesting to understand the physics and potential dangers better.
Thanks Kathy: )
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Jack
Back in the 60s we were required to work on aircraft emergency radios inside a Faraday cage to prevent the escape of unintentional transmissions. Subsequent to that decade I spent 32 years living in a mountain valley where radio communications and other sources of RF energy were absent. I've been suspect of the consequences of any form of RF since my AF training and quick to express my opinion on the subject, usually to the clueless younger generations. I believe being subjected to even low power RF signals thousands of time daily might have a cumulative effect on our health. It's only been 136 years since the first wireless transmission was sent? I'll sign off by warning you, I recently read where we should be at least 10 feet away from out routers. (not to mention smart phones) Food for thought?
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Back in the 60s we were required to work on aircraft emergency radios inside a Faraday cage to prevent the escape of unintentional transmissions. Subsequent to that decade I spent 32 years living in a mountain valley where radio communications and other sources of RF energy were absent. I've been suspect of the consequences of any form of RF since my AF training and quick to express my opinion on the subject, usually to the clueless younger generations. I believe being subjected to even low power RF signals thousands of time daily might have a cumulative effect on our health. It's only been 136 years since the first wireless transmission was sent? I'll sign off by warning you, I recently read where we should be at least 10 feet away from out routers. (not to mention smart phones) Food for thought?
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k4vud
Do you want to escape radio waves? You have to wrap your whole house sides top and bottom yeah conductive material like copper screen wire. Don't forget you have to block the windows and the doors. If you go inside Ohio home soul covered with these copper screening wire you cannot be exposed oh electromagnetic waves, that is radio waves all kinds of electromagnetic waves call impress themselves on delicate electronics parts and ruined the parts. This is why cars will not start after Oh no clear bomb with emails electromagnetic waves. Subways are usually strong enough to ruin electronic parts that's why that's why prefer one call the shortwave radios inside a Faraday cage to protect them.
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Do you want to escape radio waves? You have to wrap your whole house sides top and bottom yeah conductive material like copper screen wire. Don't forget you have to block the windows and the doors. If you go inside Ohio home soul covered with these copper screening wire you cannot be exposed oh electromagnetic waves, that is radio waves all kinds of electromagnetic waves call impress themselves on delicate electronics parts and ruined the parts. This is why cars will not start after Oh no clear bomb with emails electromagnetic waves. Subways are usually strong enough to ruin electronic parts that's why that's why prefer one call the shortwave radios inside a Faraday cage to protect them.
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Kiwi
I used to be sure of all this myself - well until. .. .! Our government reacted to a global health infection by lockong us down - and also causing our mobile phones to scream disturbing my sleep. I reacted to that terrible din, by enclosing my mobile within a steel biscuit tin. That seemed to silence my phone, well until a TXT message arrived and the phone reacted inside the biscuit tin. The tin was then swapped for a 'gap-less' wrapping of aluminium foil and the phone turned fully off. I did not expext the TXTs to get through when calls did not? That poses a question that I so far have no answer to. It also causes me some doubt and uncertainty.
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I used to be sure of all this myself - well until. .. .! Our government reacted to a global health infection by lockong us down - and also causing our mobile phones to scream disturbing my sleep. I reacted to that terrible din, by enclosing my mobile within a steel biscuit tin. That seemed to silence my phone, well until a TXT message arrived and the phone reacted inside the biscuit tin. The tin was then swapped for a 'gap-less' wrapping of aluminium foil and the phone turned fully off. I did not expext the TXTs to get through when calls did not? That poses a question that I so far have no answer to. It also causes me some doubt and uncertainty.
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NO
Dear Kathy, with high respect of your teaching I must point that drawing at 16: 01 is not right, in fact all the cage will become negatively charged almost evenly in the surface ( a little bit more at the pointed surface) if it were a sphere would be even. it can be easily seen making a drawing of the lines of inductive force perpendicular to the equipotential lines and every conductor surface is an equipotentia line, it is the graph of Laplace transform, it can be made on an elastic surface. If the drawing at 16: 01 was right there will be a steady current in the cage, by the way can you send me one of your book signed? to argentina
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Dear Kathy, with high respect of your teaching I must point that drawing at 16: 01 is not right, in fact all the cage will become negatively charged almost evenly in the surface ( a little bit more at the pointed surface) if it were a sphere would be even. it can be easily seen making a drawing of the lines of inductive force perpendicular to the equipotential lines and every conductor surface is an equipotentia line, it is the graph of Laplace transform, it can be made on an elastic surface. If the drawing at 16: 01 was right there will be a steady current in the cage, by the way can you send me one of your book signed? to argentina
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Rod
Excellent video. I really liked it. Just a small commentary about your future video on Heaviside and his modern notation for Maxwell's equations. Maybe you should mention that the modern form of Maxwell's equations is actually only modern in the sense of the period of time called modern era, which ended around 1930. Indeed, that is not the contemporary form of the Maxwell's equations. Nowadays, while all of the engineers use Heavisde version, only half of the physicists use that version regularly. The other half uses the Milkowskian version written in spacetime coordinates.
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Excellent video. I really liked it. Just a small commentary about your future video on Heaviside and his modern notation for Maxwell's equations. Maybe you should mention that the modern form of Maxwell's equations is actually only modern in the sense of the period of time called modern era, which ended around 1930. Indeed, that is not the contemporary form of the Maxwell's equations. Nowadays, while all of the engineers use Heavisde version, only half of the physicists use that version regularly. The other half uses the Milkowskian version written in spacetime coordinates.
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4SL
In 1990 I was a biomedical engineer at a southern CT hospital. The electromyography lab (patient muscle nerve diagnosis through measuring the millivolt nerve signals through needles and amplifiers. The lab was in the basement of the hospital and working fine. They were moved to the 8th floor facing Long Island Sound. Day 1 when the needle was inserted into the patients' skin, WOKO FM blared out of the speaker on the EMG machine. The 1 MW WOKO transmitter was a mile away. We had to wrap the entire room in grounded copper screening to attenuate the signal.
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In 1990 I was a biomedical engineer at a southern CT hospital. The electromyography lab (patient muscle nerve diagnosis through measuring the millivolt nerve signals through needles and amplifiers. The lab was in the basement of the hospital and working fine. They were moved to the 8th floor facing Long Island Sound. Day 1 when the needle was inserted into the patients' skin, WOKO FM blared out of the speaker on the EMG machine. The 1 MW WOKO transmitter was a mile away. We had to wrap the entire room in grounded copper screening to attenuate the signal.
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vibratingstring
My best faraday cage story comes from Freshman year at high school in Gambrills. Typical Maryland t-storm came roaring over the hill and tennis practice was quickly ended and we dashed for the building. Crazy wiind, electrical storm, spectacualr. There was a car in the parking lot with wipers and lights on. Suddenly saint elmos fire engulfed it, crawling all over the windshield then WHAM! I dont even think they knew they were hit and may not have seen the St elmos fire. But from our vantage in the doorway of the school, it was unforgettable.
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My best faraday cage story comes from Freshman year at high school in Gambrills. Typical Maryland t-storm came roaring over the hill and tennis practice was quickly ended and we dashed for the building. Crazy wiind, electrical storm, spectacualr. There was a car in the parking lot with wipers and lights on. Suddenly saint elmos fire engulfed it, crawling all over the windshield then WHAM! I dont even think they knew they were hit and may not have seen the St elmos fire. But from our vantage in the doorway of the school, it was unforgettable.
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Chuck
Kathy, at 12: 57 you show a metal ice bucket with a charge difference between the inside and the outside of the bucket.
At18: 08 you show a metal Faraday cage with a charge difference between the left and right side of the cage.
This will not happen.
The metal is conductive and no charge difference will exist from one side to the other of a conductive metal object.
Tiny amounts of charge difference could be created, however, by using a battery or DC power supply to pass an electric current through the metal objects.
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Kathy, at 12: 57 you show a metal ice bucket with a charge difference between the inside and the outside of the bucket.
At18: 08 you show a metal Faraday cage with a charge difference between the left and right side of the cage.
This will not happen.
The metal is conductive and no charge difference will exist from one side to the other of a conductive metal object.
Tiny amounts of charge difference could be created, however, by using a battery or DC power supply to pass an electric current through the metal objects.
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Andrew
Years ago I was a runner for ABC, during the 1986 Liberty Weekend event. A runner's job is to run errands and get stuff and one day, I had to source some copper foil for the engineers. They were setting up a camera on top of the WTC north tower, which had also had a large TV transmit antenna. They were concerned about the high powered radio signals inducing interference in the camera circuitry and wanted to fashion a faraday cage out of copper foil to protect it.
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Years ago I was a runner for ABC, during the 1986 Liberty Weekend event. A runner's job is to run errands and get stuff and one day, I had to source some copper foil for the engineers. They were setting up a camera on top of the WTC north tower, which had also had a large TV transmit antenna. They were concerned about the high powered radio signals inducing interference in the camera circuitry and wanted to fashion a faraday cage out of copper foil to protect it.
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Robert
Please Kathy move on to more revelent subjects most of the people I know are very aware of how faraday cages work i just will not be able to focus on information I already know. I usually love all of your videos but I keep looking for new material and Ive been skipping this one because I already am familiar with this subject and I just want you to teach me what I dont know. Thanks
Ok, the history was great the subject of the cage threw me off
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Please Kathy move on to more revelent subjects most of the people I know are very aware of how faraday cages work i just will not be able to focus on information I already know. I usually love all of your videos but I keep looking for new material and Ive been skipping this one because I already am familiar with this subject and I just want you to teach me what I dont know. Thanks
Ok, the history was great the subject of the cage threw me off
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Crusty
I've often been amazed at the insanely primitive means these geniuses used to formulate their reasoning and subsequent equations from. THIS video boggles the mind in that direction even more. The discovery of electrical principles and properties was an incredibly slow slog-- detection of anything required a detector, so. how do we detect that. thing? Truly fascinating! Thank you, Kathy!
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I've often been amazed at the insanely primitive means these geniuses used to formulate their reasoning and subsequent equations from. THIS video boggles the mind in that direction even more. The discovery of electrical principles and properties was an incredibly slow slog-- detection of anything required a detector, so. how do we detect that. thing? Truly fascinating! Thank you, Kathy!
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Robert
Please check my follow up comment, I realize that after I went on watching it that you had included the rest of the material I was wrong about that comment and said I was sorry because, as usual, you had a lot more material in the video and realized that, in fact I really was interested in all you said. Sorry, and thank you very much. I, actually love all of your videos.
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Please check my follow up comment, I realize that after I went on watching it that you had included the rest of the material I was wrong about that comment and said I was sorry because, as usual, you had a lot more material in the video and realized that, in fact I really was interested in all you said. Sorry, and thank you very much. I, actually love all of your videos.
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Will
Great explanation again, reminded me of our physics lab technician who strolled in during the Van Der Graaf generator session in school, he had long frizzy ginger hair and thinning on top.
he laid hold of the generator and the whole class laughed as his hair formed a weird shape.
Great man new exactly what he looked like and new what would happen. Cheers
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Great explanation again, reminded me of our physics lab technician who strolled in during the Van Der Graaf generator session in school, he had long frizzy ginger hair and thinning on top.
he laid hold of the generator and the whole class laughed as his hair formed a weird shape.
Great man new exactly what he looked like and new what would happen. Cheers
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SMPhotography
I have a question about Faraday cages, Is a large shed made of color bond tin with openings at either end a faraday cage. IE: a large shed for maintenance on machinery. The reason i am asking is because this shed is also a fuel up station and has been used as a Faraday cage for safety reasons which I have never agreed with.
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I have a question about Faraday cages, Is a large shed made of color bond tin with openings at either end a faraday cage. IE: a large shed for maintenance on machinery. The reason i am asking is because this shed is also a fuel up station and has been used as a Faraday cage for safety reasons which I have never agreed with.
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Mark
My dad lost one of his hearing aids and asked me to help him find it. His remote was able to connect to it anywhere in the house. I wrapped the remote in foil with just a small opening at one end, and it made a directional sensor. After about 5 minutes, I found it in the kitchen on the floor behind a chair leg. Thanks Faraday!
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My dad lost one of his hearing aids and asked me to help him find it. His remote was able to connect to it anywhere in the house. I wrapped the remote in foil with just a small opening at one end, and it made a directional sensor. After about 5 minutes, I found it in the kitchen on the floor behind a chair leg. Thanks Faraday!
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Philip
Surely, there must be some very low frequency at which DC to RF transition happens (I should look it up.
For the magnetic compass in the aircraft, one would expect that frequency to be such that any reasonable manoeuvrer (inc fighters) would be acceptable so one complete roll per second wouldn't have any effect.
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Surely, there must be some very low frequency at which DC to RF transition happens (I should look it up.
For the magnetic compass in the aircraft, one would expect that frequency to be such that any reasonable manoeuvrer (inc fighters) would be acceptable so one complete roll per second wouldn't have any effect.
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Mark
Sorry about the shameless plug? Nah, you are either sorry or shameless unless you are arguing that quantum physics can be usefully applied to grammar.
Oh, and good to see the gladioli squarely in shot. 'A' grade science shows should neglect neither visual aesthetics nor the proper use of English.
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Sorry about the shameless plug? Nah, you are either sorry or shameless unless you are arguing that quantum physics can be usefully applied to grammar.
Oh, and good to see the gladioli squarely in shot. 'A' grade science shows should neglect neither visual aesthetics nor the proper use of English.
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