12:43 -- Jacobi did publish a picture of his rheostat in 1842: Jacobi, M.H. (1842) "Beschreibung eines verbesserten Voltagometers" (Description of an improved voltagometer) Bulletin Scientifique publié par l’Académie impériale des sciences de Saint-Pétersbourg, 10: columns 285-288. Three diagrams appear after column 288.
@@Kathy_Loves_Physics -- You're welcome. 🙂 If you want a translation of the article, I could provide one. (It would take a few days to type it up. And I'd need an e-mail address to which I could send it.)
Good find. However; he saw Wheatstone's rheostat in 1840, but not published his book until 1842, so why Kathy implied Wheatstone had seen Jacobi’s before 1840 (20:39) by repeating the quote “quite impossible” in the text? The whole sentence means otherwise.
@@htooloo365 -- Yes. At 8:28 the text of Jacobi's article states that Jacobi thought that Wheatstone could Not have known about Jacobi's rheostat when Wheatstone invented his own version of a rheostat. So in Jacobi's opinion, they had invented the rheostat independently. The text originally appeared on p. 21 of: Jacobi (1840) "On the principles of electro-mechanical machines" Tenth Meeting of the British Association for the Advancement of Science: Notices and Abstracts of Miscellaneous Communications to the Sections pp. 18-24.
When I was a kid, remember my physics teacher muttering darkly that "It isn't Wheastone's bridge, it's a Christie's bridge"...the text-books said otherwise. Thanks for clearing that up!!
As a child of the late 20th Century, I am often humbled by science history. I was taught about electrical voltage, current and the relationship between them (resistance, capacitance and inductance) almost as if Ohm's Law always been understood and accepted since the "beginning of time". It is fascinating to learn how this was not the case and that even among the best and brightest minds of their time, they was much uncertainty, disagreement and debate. It is remarkable that the "idle thoughts" of a handful of curious minds over 150 years ago led to the splitting of atoms, spacecraft that travel the Universe and supercomputers that we can carry around in our pockets.
Another home run! I would like to add as an aircraft technician, this concept is used to measure the density of the fuel by weight, using capacitors instead of resistors. The variable capacitance being the fuel compared to a known reference capacitance.
where can I read more about this in your application? I am a marine technician specializing in electronics, networks, and sensors... also working on my own engine instrumentation systems. thanks
Jacobi’s “voltagometer” (“an improved rheostat markedly better than that by Poggendorf”) worked by suspending platinum wires in separate mercury containers. The mercury containers are connected by a platinum wire that can be raised or lowered to increase or decrease the length of platinum generated by the current, and hence the resistance. Got this from a Dutch book from 1860: “Over het meten van den galvanischen geleidingsweerstand inzonderheid bij metalen” By Hendrik W. Schroeder van der Kolk Incidentally, I like to find references in Dutch scientific literature, because traditionally, any educated Dutch person would have spoken German, English and French (and know Latin), so they were usually aware of more international publications than most).
The context you use to describe these basics of electricity and magnetism is most enlightening. As-in the true historical machinations and personalities behind these leap-frog discoveries. Thank you Kathy.
This is the first time I've heard a Wheatstone story that didn't include the fear of public speaking anecdote - which means I got to learn something. Well done.
Funny thing, I mentioned that he was scared of speaking in my last video and I was going to mention it again, but cut it out as it didn't need to be said twice. Glad I did.
Thanks, never heard of Moritz von Jacobi before, but I did hear of use his Maximum power theorem. Basically always match impedances for maximum power transfer, it is one of those things that is as fundamental as ohms law and taken for granted. In the RF world most circuits are designed to have 50 ohms on their inputs (e.g. reference clocks) and outputs (e.g antennas). In designing high speed address and data buses in computers the impedance of all the transmission lines on the PCB's (Printed Circuit Boards) would all be designed to match the input and output of everything on the buses (e.g. memory, I/O and CPU) which is typically 50 to 60 ohms. I love your video as always! Thank you.
I was tempted to mention his maximum power equation but the video was already so long that I had to cut it. Jacobi deserves his own video honestly. Glad you liked this video and thanks for always commenting
More famous than Moritz probably is his brother Carl Gustav Jacob Jacobi (en.wikipedia.org/wiki/Carl_Gustav_Jacob_Jacobi) at least in mathematical circles.
As a former EE student, these names, these people are the Hallowed saints of electronics (Voltaire, Ohm, Wheatstone, etc). Thank you so much for bringing them to life, and for showing them to be human; warts, misrepresentations and all.
Lots of theft like this happens from grad students to professors today. It's just really hard to track. This videos are great for being reminded of this re-writing of history by the victors.
According to my late father the variable resistor was invented by either Sam Rheostat or Sam Potentiometer. When I was very young I just discovered that my father knew everything about inventions. It did surprise me how many inventors were named Sam.
@@Kathy_Loves_Physics Indeed. He was also a skilled raconteur and notorious punster, not to overlook his engineering prowess. Rarely a day goes by that I don't observe something that would have amused him. He was a PE and there are so many technical skills I learned at his elbow. He would have enjoyed your videos too. One of the places he worked during his GE career was the high voltage laboratory. I got to go there once on family day. th-cam.com/video/gNlkEK9WhyY/w-d-xo.html
That is so interesting! And I love those old videos. I am working on a video about James Joule and then after that I’m going to do a video on three phase current but after that I’m going to do a video on Charles Steinmetz who invented the first lightning machine that was powerful and didn’t just look like lightning and he works for GE so you probably saw some of his devices! I am sorry I missed out on meeting your father - I think we would have liked each other even if I don’t mention Sams enough.
@@Kathy_Loves_Physics he spent years working within feet of where Steinmetz worked but they were not contemporaries. GE is a dirty word in my former hometown due to numerous things such as their casual disposal of PCBs back in the day. Some great science and technology came out of there however.
This reminds me of the great rivalry between George Device (supposed relative of the Pendel witch Jennet Device), Isambard Widget, and Lord Aubrey Millington, third viscount Doohicky.
Another interesting an energetic presenttion. I worked in the Telephone Company in Ireland many years ago, where we used the Wheatstone bridge to measure the distance to a short circuit in an underground cable.
@@banehawi You know, we show our age knowing about cable testing. So much of the plant today is coaxial and digital. Bit error rate testers are now cheap enough that all the technicians carry one. They have to test a customer circuit before completing the order. One thing craftsmanship and the technical skills have deteriorated. After the company laid me because of the AT&T split I went into business for myself. some of the people working for me couldn't use an Ohmmeter. One didn't know how to polarize a line, He'd never heard of "tip and ring." I'm very happily retired now.
Great video! I just discovered this channel and I'm enjoying it so much! In this case, however, I do disagree with Kathy's interpretation of a source (that she presents). At 8:21, Kathy says that Wheatstone claims he and Jacobi made an independent discovery, but that Jacobi claimed this was "quite impossible". However, the full sentence, as shown in the video, reads "Now, it is quite impossible that he [Wheatstone] should have had the least notice of my [Jacobi's] instrument." This means that Jacobi claims that it is impossible that Wheatstone was aware of Jacobi's invention ("to have notice"="to be aware"). In other words, Jacobi is claiming that their inventions were independent. He and Wheatstone are in agreement on this, at least per the printed article.
Would be amazing to see film footage of these early "electronic" inventors at work in their laboratories, if only that was possible. Would be great to see close ups of them making all the inventions at the various stages.
The Wheatstone Bridge was one of the early circuit builds I did as a child using my Heath Kit set from the mid 1970's. The Heath Kit was plastic blocks with a component inside and placed on a LEGO looking base plate. The blocks were then tied together with pin clips and wires to make a circuit. One of the more complicated builds was a 3 transistor radio, multi-meter sound generator, and timing counters.
When I was 11 I built the Heathkit Vacuum Tube Volt Meter (a truely useful and accurate bench meter) and when I was 14 I built the Heathkit oscilliscope. I loved those kits.
@@pjh9104 My late dad went through electronics correspondence school through Bell & Howell and built the projects you stated. Subsequent courses used the built items to perform tests.
Built a Health Kit 25" TV while taking an electronic correspondence class that the VA paid 90% of. Wish more young kids would experiment with wires & electronics. Doubt if 1% of people even know how to use a soldering iron or gun.
I worked in a research and testing facility for a few years. When checking some background information on strain gauge measurements (you should know some basics of what you do), I also got to know Wheatstone's bridge. The measuring amplifiers nowadays are quite easy, you click on a button in the software to set all strain gauges to zero before the measurement, but in "ancient" times so had to tune one of the resistors in the Wheatstone bridges for each individual strain gauge by hand to start the measurement at 0 (or whatever value you liked).
New follower here... I've worked in electronics most of my life and understand it as well as the next guy... I guess, but I've only known little snatches here and there of the history behind it all. I love your videos. Gets me closer to something I've always taken for granted.
Great history lesson, another colorful character in the annals of science. So much for science being solely an intellectual discipline. I was unaware of the history behind the Wheatstone Bridge.
This is the first mention of the Wheatstone Bridge I've heard since I left Ma Bell many years ago. Years ago telephone central offices had a test desk. In most cases it looked like one of the old corded switchboards operators worked from. The test desk took trouble reports from customers, tested them, dispatched a technician if necessary and then closed the ticket after noting what had been done to clear the problem. Most of them have disappeared if not because most testing is now done in the field by the technicians and the whole process has become computerized. Every test desk had a Wheatstone Bridge mounted in a drawer. The test deskman (old terminology) used it to measure resistances on cable troubles using a Murray Test Or a Varley Test. A technician would call in and the testdesk using the cable plats send him to the farthest end of the cable and short circuit the pair of wires in trouble. The pair of wires would be connected to the bridge. If one side of the pair was grounded he would measure the resistance through the short circuit to ground. Then he'd reverse the bridge and look thought short in the other direction. Using a math formula and consulting the cable plats showed the overall resistance and capacitance the cable he could put the technician within a few feet of the problem location. I the cable was running in the air the outside temperature was factored in. Buried cable was consistent in temperature. Mixed buried and aerial cable caused a fluctuation in the math but a good test desk man could still get you very close. At the time which was before the 1970s all the test deskmen were cable repairmen and a few equipment technicians tired of working outside in the weather. Some of the equipment technicians would transfer into the central office as Switchmen. That all changed in 1970 when the company women in these technical position to satisfy the Equal Employment Opportunity Commission. Without the field experience most of the women did the testing poorly. for the women it was all about money. The technical positions were filled with men and they paid better than the mostly clerical positions women were in. Almost immediately the company developed computerized testing. Once it had saturated the system almost all the testdesk personnel were downgraded to a clerical position that paid less and required less skill. The line cards were removed and the records were computerized. In an entire region there were one or two testdesk technicians and his testdesk used trunks to test in any troubles for the entire region. The Wheatstone Bridges. Eventually the Wheatstone Bridges disappeared. So did almost all of the technicians. The system is so computerized that people with those skills are no longer needed. That and the reduction of telephone lines on copper. Computers now compress thousands of telephones on what once could only carry one. Now you can get your telephone on a coax cable carrying your television signal and Internet service. Or you can just use a cellphone with a satellite dish for television. The installers now using technician as a title are installers. They have so little knowledge of equipment and electronics they are not technicians in reality The Wheatstone Bridge left with the technicians and they aren't coming back.
@@gpwgpw555 Yeah, that was the old one. I would sometimes go inside to cover someone on vacation. We had a "temporary" test center using 2A cabinets. You must be another old timer. We're disappearing fast. It seems like someone passes every other month. And not very old either. The business really changed. The smaller COs have no one working in them. The cable techs make the inside connections, at least they used to until the SMAZ frames. Good Luck.
@@robertcuminale1212 42 years as a switchman in Oklahoma City. I loved 37 years of it. In the last five years we became customer driven. meaning we did not fix anything unless customers reported trouble.
WOW, never knew any of this. Have a Wheatstone bridge in my collection that I got from a deceased estate for measuring resistors precisely, but the first Im hearing of these other people ie: as Jacobi and Christie. Once again much thanks for these stories.
Vitally necessary (for those of us into such topics), wonderfully researched and entertainingly delivered at a perfect pace. The highlighting of the documents to evidence what was said and when is a great touch. Superb :)
Thanks for taking the time to share. Such a simple circuit but very important for the first precision or matched resistors . It all seems so simple and obvious now but in 1839 sourcing an electric charge,copper wire or other metal conductive wire took some scrounging as well as quantifying the electric charge s intensity and flow. The "Wheatstone" and Galv-meter led to the first calibration of tools to measure Volts Amperes and Ohms.
Thank you for this marvelously detailed video, I had time only for 5 or 6 minutes before skipping to the end. On mentioning " using Wheatstone bridge circuit for use with strain guages" to a Gloucester Engineering Manager years ago, It was mentioned he was associated with Gloucester and worked for Marconi .
Thanks for putting the fun into math and science. I watch all of your videos over and over. I have an interest in math and science but limited ability so that is why even though I have taken lots of college classes I do not work in the field and I have lots of bad memories in college with great suffering in tests and exams. But I watch your videos over and over and the joyous fun comes back to studying math and science because we see the human side to it.
Hey, Jacobi didn't write that it was impossible that they had come up with the same idea independently, he wrote that it was impossible that Wheatstone "should have had the least notice of my instrument", implying that he was convinced that they HAD come up with the same idea independently. Thanks for these videos!
And in the next sentence he praises Wheatstone for the wide variety of uses as a measuring tool that Wheatstone found for this device while himself only used it as a regulator. This is an extra argument for independent simultaneous discovery since they both created their device for different purposes.
@@christianbarnay2499 people at that time would choose politeness over direct confrontation to cope with public known figures stealing their ideas and decide to be the bigger person by attributing praise on the stealer not for stealing but in order to showing no hard feelings but they had internally recognised their own acheivements and felt it
@@kevindoom You can still politely criticize the attitude of someone, just like Cooke did when he clearly disapproved Wheatstone claiming their collaborative work as his own. When Jacobi says that Wheatstone and himself created the same instrument independently for different purposes (Jacobi needed a regulating device, Wheatstone needed a measuring device) there are no valid reasons to not believe him.
@@christianbarnay2499 whetstone was declaring that he independantly came up with it but in the exact same way the exact same way it was obvious of course Jacobi knew but he decided to deal with it politely
We used a Wheatstone bridge to create a gas detector. Platinum wires were 2 legs of the Wheatstone bridge. One wire was enclosed in a glass tube and the other platinum wire was in a gas stream sampling from a vacuum pump hooked to a small hose. If methane or other volatile gas is introduced to that open wire, it raises the temperature and changes the resistance in the platinum wire. A chromatograph could then be built by injecting a set volume into a "column" of silica gel which slowed the heavy molecules down. A carrier gas was used to keep a steady flow over the detector filament. Helium could be used or dried air was commonly used in the more rudimentary instruments. First gas to come out is methane and then successively larger molecules. The bridge records the change in resistivity to a chart recorder (today it would be a data logger to display on a computer.) Very simple and important on a drill rig attempting to detect entrained gases in the drilling fluid, very robust and non-fragile.
The basic bridge arrangement can also be used with two inductors or two capacitors as the top or bottom two elements, and that makes a very sensitive way to compare capacitors or inductors. The circuit can also be used with a gain element like a tube or transistor to make a very accurate oscillator or filter. Hewlett-Packard's first product was an audio oscillator that used such a bridge.
I really liked listening to your lecture and as informative as you were, I was deeply happy with you as an endearingly sweet and quirky woman who reminded me of some of the most beloved in my family who, like you, always have something new for me to learn. Thank you, I look forward to watching more of your videos but now, as your subscriber.
Great! The history behind this ubiquitous concept that we use today in school lab to highly sophisticated electronic control system is very very fascinating. Thank you.
In school i built a cryogenic fluid temperature measuring device based on the Wheatstone Bridge circuit. Nice to hear the history and especially the evolution of thought. We all learn from each other....to be better.
I worked as a Technician for a resistor company back in the 70's & 80's. We used our own factory built high speed testers and these testers were built with the wheatstone principles, but were far more complex. We had a decade resistor network that was set to the nominal value, two tolerance dials which set the plus and minus tolerance of the resistor under test. And finally a compensation pot that nullified internal resistance. Instead of two coaxial cables going to the test resistor, there were four and a compensation network was also applied to these cables. Then it really got complicated in that we had to test on the 60 cycle crossover. This was to keep any outside interference from the test. That crossover detection went to the logic circuit where it fed an "and" gate along with the bridge sample and the result "good" 1 or "bad" 0 went to a shift register. That's about it except that I did not mention that the sample signal is developed by a bi-latteral switch which is running at 60Hertz.
OMG In America you have Edison who on account did innovations based on other inventors works, in the UK we have Wheatstone....What a story! Great video!!!!!!
The last time I used a Wheatstone Bridge was as a college student 20 years ago something with strain gages and pressure transducers. With my soldering technique, it was a good thing I was going into mechanical engineering.
Very interesting how the facts don't seem to ever percolate to the surface. Well done. I'm a retired EE and son of an EE professor. Sadly, I do not find this at all surprising. I never heard of Tesla until I was 22, other than the magnetic field units, for instance.
Whatever you call it, the Wheatstone bridge had a huge influence in accurately measuring the surface stress in mechanical parts using strain gauges (resistance varies with the tension applied to a metallic wire). Today, and for a very long time, strain gauges are sold in a Wheatstone bridge array which will automatically compensate for fluctuations due the resistance change brought on by the thermal expansion or contraction of the metal to which the strain gauge array is affixed.
The long coil variable resistors were in common use into the 1950's. I have salvaged several old Fire Alarm systems that used them to account for different numbers of fire horns installed.
I think I must have found from somewhere (maybe a battery charging circuit?) a crude variable resistor, being a copper wire wound around a piece of asbestos board about 3in by 7in. The wiper was conected to a slider the top edge of the bread slice board and the feed to the first wire in the low position on the board. Interesting
Thanks for another great talk. Wheatstone also invented the ABC telegraph, which had the advantage of not needing expert telegraph operators at each end. Continued to be used till the 1930's in remote island locations without telegraph operators. Wheatstone seems to have been a bit of a dodgy character.
Alexander Bain invented the ABC Telegraph (it’s in the video) - Wheatstone plagiarised it. He also discovered the earth battery that transatlantic telegraphy uses.
@@da8ish1 Think just in United Kingdom. Was used in the Highlands and Islands as no need for expert telegraphers which was the drawback of the Morse system as it was used in practice.
At 8:30 into the lecture I believe that there is a significant error pending your understanding of physics, but of the interaction between Jacobi and Wheatstone. Jacoby did not say that Wheatstone must have known about his instrument, in fact the opposite. he said it was "impossible the he should have had the least notice", which speaks to acknowledging that the idea was not stolen but done in parallel. He then goes on to in fact praise Wheatstone for discovering "a new method of measuring these current and of determining the different elements or constants, which enter into the analytical expressions, and on which depends the actions of any galvanic combination." He also acknowledges the sharing of valuable results from an yet published paper, again acknowledging Wheatstone. Not the words of a wounded ego, I think. Nor do I think negatively of your efforts here. The history was very well done.
I was glad to see that you did make it clear that Wheatstone’s bridge is balanced. I so dislike the misuse of the term by so many students who must get it from their teachers. Measuring zero current is so much easier than an actual current as the linearity of the measurement does not matter. Knowing the lost in translation and loss of references is interesting. Germanic use of references is different, or so I have been told, by those who fail to reference my work.
Hello Kathy, I'm not a total geek but I have to laugh hearing "Wheatstone Bridge" start my HVAC education in the 70's and soon after became a tech for Honeywell and offering classes on Honeywell products to contractors in the industry. The Wheatstone Bridge or reostat was a topic that was reviewed often . Thank you!
Great video. This is exactly the period of electrical history that I am interested in. (I'm working on a suspended coil galvanometer right now) Liked and Subbed.
I remember college classes that had Wheatstone bridge circuits, my impression is professors use this bridge for circuit analysis problems for homework and exams. But other than that, nobody uses it. Then out into the real world becoming involved with jobs that have strain gages, that's where I saw the value of the Wheatstone bridge. There is very very little change in resistance in the strain gage itself, probably not enough to reliably measure without the Wheatstone bridge. With the bridge, it becomes easy to measure (of course need reliable low level volt meter and stable excitation). Strain gages can be fascinating considering they accurately measure stress in structures whether it be building I-beams, car frames, or force-moment balances.
8:27, the Jacobi quote you highlight says the opposite of what you state. Jacobi says it is improbable for Wheatstone to have known (had notice of) of his instrument, ie he thinks it was an independent invention, though later.
When studying electrical engineering, students barely have time to learn about the Wheatstone bridge and it's applications; hardly have time to learn about this history. However, now that Kathy has done all this legwork, EE students should watch this. In physics classes, much more history is provided in general physical principles like what are electrons doing, and who and how they figured this out.
This is my 2nd video of this Kathy person. She's certainly got a good angle on tech, and she tells a good story! During the first video, the thought occurred, as my orbital muscles fatigued from tracking all the left and right motion across the bottom of the screen: would young Kathy be able to talk if someone tied her hands? 0:02 I got
Practical uses of the Wheatstone Bridge include load cells and strain gages. Force and dimension change are able to be computed after gluing resistors to materials that will undergo stress. Being able to solve the Wheatstone bridge means you can make your own load cells on the cheap.
In your Ohm’s Law video, you mentioned that just as the unit of resistance, the ohm, is represented by the Greek letter omega (Ω), its reciprocal, the unit of conductance, the “mho,” is represented by an inverted omega. Some years ago, the unit of conductance was officially renamed the “siemens,” after the German inventor and founder of the Siemens company. In the 1960s I remember that the sensitivity of voltmeters was still expressed, at least in the US, in “micromhos.”
It's interesting to follow up this video with the article on Wheatstone in the Wikipedia. At first sight the article gives credit to Cooke and Christie. Wheatstone was very prolific and worked on spectroscopy and acoustics as well.
Interesting you mentioned a means of testing low resistance values. . . Quite some years ago, I designed and built a 10 Amp "Earth Resistance" Tester. . .. Recently I had a failed Inverter, it tripped all its Battery feed breakers.. . I tested its DC input resistance with my "Earth Resistance" tester that uses an internal 12V battery and accurate 1 Ohm resistor, and found the DC input to that Inverter was down to 0.028 Ohm.. . . Years earlier there was a break on a UK-USA Cable, the special time fault locator was out of action, so the UK pulled out an old Wheastone Bridge and measured the fault o just of the USA coast.
We used the principles for the wheat stone bridge to calibrate or certify many measurement tools but the most unique application was used in gas chromatography where using one leg measured heat loss from a gas sample stream while the other leg was maintained as a standard. It's more than a paragraph, real time process instruments are complicated
“Prof. Wheatstone has shown me an instrument, found on exactly the same principle as mine... Now it is quite impossible that he should have had the least notice of my instrument.” Unless there is mistakes in the translation from German to English, the text suggested that Wheatstone has came up with the rheostat using Ohm law, and also that it is impossible for Wheatstone to see Jacobi' instrument prior. A simple explanation why you could not find Jacobi's rheostat drawing could be he has never published it, since he thought the rheostat was insignificant comparing to the motor. If I am not mistaken Wheatstone could not have seen it. May be some other ideas was lifted by Wheatstone, but for the rheostat, knowing Ohm law he could come up with it by himself.
"A simple explanation why you could not find Jacobi's rheostat drawing could be he has never published it" Such a drawing exists and he did publish it - check out the pinned comment.
Great Video! I first learned about the Wheatstone bridge in freshman physics: electricity and magnetism came right after mechanics and heat. Concerning Christie, sic transit gloria mundi. Christie was not the first nor the last to be unjustly forgotten by history because of unscrupulous self-promotors.
I've been to the Royal Society and read the minutes of the meeting where Wheatstone presented the bridge circuit to the other members. In the minutes he is quoted as saying that he would like to present to them, a circuit which was devised by, and given to him, (Wheatstone), by a Mr Christie.
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12:43 -- Jacobi did publish a picture of his rheostat in 1842:
Jacobi, M.H. (1842) "Beschreibung eines verbesserten Voltagometers" (Description of an improved voltagometer)
Bulletin Scientifique publié par l’Académie impériale des sciences de Saint-Pétersbourg, 10: columns 285-288. Three diagrams appear after column 288.
Wow! Thank you thank you thank you! I don’t speak German or French and I was having a heckuva time finding it. ❤️❤️❤️
@@Kathy_Loves_Physics -- You're welcome. 🙂 If you want a translation of the article, I could provide one. (It would take a few days to type it up. And I'd need an e-mail address to which I could send it.)
Good find. However; he saw Wheatstone's rheostat in 1840, but not published his book until 1842, so why Kathy implied Wheatstone had seen Jacobi’s before 1840 (20:39) by repeating the quote “quite impossible” in the text? The whole sentence means otherwise.
@@htooloo365 -- Yes. At 8:28 the text of Jacobi's article states that Jacobi thought that Wheatstone could Not have known about Jacobi's rheostat when Wheatstone invented his own version of a rheostat. So in Jacobi's opinion, they had invented the rheostat independently. The text originally appeared on p. 21 of: Jacobi (1840) "On the principles of electro-mechanical machines" Tenth Meeting of the British Association for the Advancement of Science: Notices and Abstracts of Miscellaneous Communications to the Sections pp. 18-24.
@@Kathy_Loves_Physics did you ever get back to Kevin Byrne who said he could translate for you.
When I was a kid, remember my physics teacher muttering darkly that "It isn't Wheastone's bridge, it's a Christie's bridge"...the text-books said otherwise. Thanks for clearing that up!!
very nice and helpful to bring their names back to life
As a child of the late 20th Century, I am often humbled by science history. I was taught about electrical voltage, current and the relationship between them (resistance, capacitance and inductance) almost as if Ohm's Law always been understood and accepted since the "beginning of time". It is fascinating to learn how this was not the case and that even among the best and brightest minds of their time, they was much uncertainty, disagreement and debate. It is remarkable that the "idle thoughts" of a handful of curious minds over 150 years ago led to the splitting of atoms, spacecraft that travel the Universe and supercomputers that we can carry around in our pockets.
Another home run! I would like to add as an aircraft technician, this concept is used to measure the density of the fuel by weight, using capacitors instead of resistors. The variable capacitance being the fuel compared to a known reference capacitance.
where can I read more about this in your application? I am a marine technician specializing in electronics, networks, and sensors... also working on my own engine instrumentation systems. thanks
And so far it has worked perfectly! I have never ran out of fuel whilst flying, yet………….
Jacobi’s “voltagometer” (“an improved rheostat markedly better than that by Poggendorf”) worked by suspending platinum wires in separate mercury containers. The mercury containers are connected by a platinum wire that can be raised or lowered to increase or decrease the length of platinum generated by the current, and hence the resistance.
Got this from a Dutch book from 1860:
“Over het meten van den galvanischen geleidingsweerstand inzonderheid bij metalen”
By Hendrik W. Schroeder van der Kolk
Incidentally, I like to find references in Dutch scientific literature, because traditionally, any educated Dutch person would have spoken German, English and French (and know Latin), so they were usually aware of more international publications than most).
Kathy! You are just a great story teller! For me that's by far the best way to teach science to the public by telling its history! Thank you!
Hans ,quite agreeing with you!
I third that!
Great story teller, but please don't flap your arms about so much, I got nauseous watching them.
The context you use to describe these basics of electricity and magnetism is most enlightening. As-in the true historical machinations and personalities behind these leap-frog discoveries.
Thank you Kathy.
Wonderful! Thank you. Knowing the history of inventions is so helpful in really understanding the components!
This is the first time I've heard a Wheatstone story that didn't include the fear of public speaking anecdote - which means I got to learn something. Well done.
Funny thing, I mentioned that he was scared of speaking in my last video and I was going to mention it again, but cut it out as it didn't need to be said twice. Glad I did.
always disliked those things, professor did a poor job(don't really need them 2 fix stuff) since the whole class was lost.
Thanks, never heard of Moritz von Jacobi before, but I did hear of use his Maximum power theorem. Basically always match impedances for maximum power transfer, it is one of those things that is as fundamental as ohms law and taken for granted. In the RF world most circuits are designed to have 50 ohms on their inputs (e.g. reference clocks) and outputs (e.g antennas). In designing high speed address and data buses in computers the impedance of all the transmission lines on the PCB's (Printed Circuit Boards) would all be designed to match the input and output of everything on the buses (e.g. memory, I/O and CPU) which is typically 50 to 60 ohms.
I love your video as always! Thank you.
I was tempted to mention his maximum power equation but the video was already so long that I had to cut it. Jacobi deserves his own video honestly. Glad you liked this video and thanks for always commenting
More famous than Moritz probably is his brother Carl Gustav Jacob Jacobi (en.wikipedia.org/wiki/Carl_Gustav_Jacob_Jacobi) at least in mathematical circles.
This channel is so important. Oh Kathy has new- and I’m learning so much about these achievements! Great. I love this
Glad you enjoy it!
I agree, it is a wonderful channel. Essential viewing for me.
I'm so happy to have discovered this TH-cam channel! Wonderful content charmingly presented.
Love your enthusiasm, Kathy.
Thanks
As a former EE student, these names, these people are the Hallowed saints of electronics (Voltaire, Ohm, Wheatstone, etc). Thank you so much for bringing them to life, and for showing them to be human; warts, misrepresentations and all.
Voltaire was a philosopher among other things.
I believe you mean Volta. Alessandro Volta, the Italian physicist.
Volta, not Voltaire, sorry
Voltaire? .Really!? What about Ampère?
Voltaire does not belong here, his contribution is about other stuff
@@geertfdevries9518 Though it must be said that Voltaire could electrify his readers.
Lots of theft like this happens from grad students to professors today. It's just really hard to track. This videos are great for being reminded of this re-writing of history by the victors.
Yes, the Pulsar springs to mind.
...The graduates are used like slaves or tools on occasion for the overseeing prof.
It's getting better though as a lot of research papers today will have literally a dozen or more participants.
Kathy rocks! 😊
According to my late father the variable resistor was invented by either Sam Rheostat or Sam Potentiometer. When I was very young I just discovered that my father knew everything about inventions. It did surprise me how many inventors were named Sam.
Your father sounds like a hoot.
@@Kathy_Loves_Physics Indeed. He was also a skilled raconteur and notorious punster, not to overlook his engineering prowess. Rarely a day goes by that I don't observe something that would have amused him. He was a PE and there are so many technical skills I learned at his elbow. He would have enjoyed your videos too.
One of the places he worked during his GE career was the high voltage laboratory. I got to go there once on family day. th-cam.com/video/gNlkEK9WhyY/w-d-xo.html
That is so interesting! And I love those old videos. I am working on a video about James Joule and then after that I’m going to do a video on three phase current but after that I’m going to do a video on Charles Steinmetz who invented the first lightning machine that was powerful and didn’t just look like lightning and he works for GE so you probably saw some of his devices! I am sorry I missed out on meeting your father - I think we would have liked each other even if I don’t mention Sams enough.
@@Kathy_Loves_Physics he spent years working within feet of where Steinmetz worked but they were not contemporaries.
GE is a dirty word in my former hometown due to numerous things such as their casual disposal of PCBs back in the day. Some great science and technology came out of there however.
This reminds me of the great rivalry between George Device (supposed relative of the Pendel witch Jennet Device), Isambard Widget, and Lord Aubrey Millington, third viscount Doohicky.
Another interesting an energetic presenttion. I worked in the Telephone Company in Ireland many years ago, where we used the Wheatstone bridge to measure the distance to a short circuit in an underground cable.
See my reply on that same method. Did you call the tests Varley or Murray tests? We also used it to find grounds.
@@robertcuminale1212 Think it was Varley..
@@banehawi You know, we show our age knowing about cable testing. So much of the plant today is coaxial and digital. Bit error rate testers are now cheap enough that all the technicians carry one. They have to test a customer circuit before completing the order. One thing craftsmanship and the technical skills have deteriorated. After the company laid me because of the AT&T split I went into business for myself. some of the people working for me couldn't use an Ohmmeter. One didn't know how to polarize a line, He'd never heard of "tip and ring."
I'm very happily retired now.
Great video! I just discovered this channel and I'm enjoying it so much!
In this case, however, I do disagree with Kathy's interpretation of a source (that she presents). At 8:21, Kathy says that Wheatstone claims he and Jacobi made an independent discovery, but that Jacobi claimed this was "quite impossible". However, the full sentence, as shown in the video, reads "Now, it is quite impossible that he [Wheatstone] should have had the least notice of my [Jacobi's] instrument." This means that Jacobi claims that it is impossible that Wheatstone was aware of Jacobi's invention ("to have notice"="to be aware"). In other words, Jacobi is claiming that their inventions were independent. He and Wheatstone are in agreement on this, at least per the printed article.
Would be amazing to see film footage of these early "electronic" inventors at work in their laboratories, if only that was possible. Would be great to see close ups of them making all the inventions at the various stages.
The Wheatstone Bridge was one of the early circuit builds I did as a child using my Heath Kit set from the mid 1970's. The Heath Kit was plastic blocks with a component inside and placed on a LEGO looking base plate. The blocks were then tied together with pin clips and wires to make a circuit. One of the more complicated builds was a 3 transistor radio, multi-meter sound generator, and timing counters.
When I was 11 I built the Heathkit Vacuum Tube Volt Meter (a truely useful and accurate bench meter) and when I was 14 I built the Heathkit oscilliscope. I loved those kits.
@@pjh9104 My late dad went through electronics correspondence school through Bell & Howell and built the projects you stated. Subsequent courses used the built items to perform tests.
Built a Health Kit 25" TV while taking an electronic correspondence class that the VA paid 90% of. Wish more young kids would experiment with wires & electronics. Doubt if 1% of people even know how to use a soldering iron or gun.
I worked in a research and testing facility for a few years. When checking some background information on strain gauge measurements (you should know some basics of what you do), I also got to know Wheatstone's bridge.
The measuring amplifiers nowadays are quite easy, you click on a button in the software to set all strain gauges to zero before the measurement, but in "ancient" times so had to tune one of the resistors in the Wheatstone bridges for each individual strain gauge by hand to start the measurement at 0 (or whatever value you liked).
Another most enjoyable "inside story", Kathy. Good presentation and graphics. Thank you!
New follower here... I've worked in electronics most of my life and understand it as well as the next guy... I guess, but I've only known little snatches here and there of the history behind it all. I love your videos. Gets me closer to something I've always taken for granted.
Great history lesson, another colorful character in the annals of science. So much for science being solely an intellectual discipline. I was unaware of the history behind the Wheatstone Bridge.
I just learned the history of the bridge myself! Yeah, science is not always pretty or kind.
You are a natural Teacher. Thanks.
This channel is GREAT!
This is the first mention of the Wheatstone Bridge I've heard since I left Ma Bell many years ago.
Years ago telephone central offices had a test desk. In most cases it looked like one of the old corded switchboards operators worked from. The test desk took trouble reports from customers, tested them, dispatched a technician if necessary and then closed the ticket after noting what had been done to clear the problem. Most of them have disappeared if not because most testing is now done in the field by the technicians and the whole process has become computerized.
Every test desk had a Wheatstone Bridge mounted in a drawer. The test deskman (old terminology) used it to measure resistances on cable troubles using a Murray Test Or a Varley Test. A technician would call in and the testdesk using the cable plats send him to the farthest end of the cable and short circuit the pair of wires in trouble. The pair of wires would be connected to the bridge. If one side of the pair was grounded he would measure the resistance through the short circuit to ground. Then he'd reverse the bridge and look thought short in the other direction. Using a math formula and consulting the cable plats showed the overall resistance and capacitance the cable he could put the technician within a few feet of the problem location. I the cable was running in the air the outside temperature was factored in. Buried cable was consistent in temperature. Mixed buried and aerial cable caused a fluctuation in the math but a good test desk man could still get you very close.
At the time which was before the 1970s all the test deskmen were cable repairmen and a few equipment technicians tired of working outside in the weather. Some of the equipment technicians would transfer into the central office as Switchmen. That all changed in 1970 when the company women in these technical position to satisfy the Equal Employment Opportunity Commission. Without the field experience most of the women did the testing poorly. for the women it was all about money. The technical positions were filled with men and they paid better than the mostly clerical positions women were in. Almost immediately the company developed computerized testing. Once it had saturated the system almost all the testdesk personnel were downgraded to a clerical position that paid less and required less skill. The line cards were removed and the records were computerized. In an entire region there were one or two testdesk technicians and his testdesk used trunks to test in any troubles for the entire region. The Wheatstone Bridges. Eventually the Wheatstone Bridges disappeared. So did almost all of the technicians. The system is so computerized that people with those skills are no longer needed. That and the reduction of telephone lines on copper. Computers now compress thousands of telephones on what once could only carry one. Now you can get your telephone on a coax cable carrying your television signal and Internet service. Or you can just use a cellphone with a satellite dish for television. The installers now using technician as a title are installers. They have so little knowledge of equipment and electronics they are not technicians in reality
The Wheatstone Bridge left with the technicians and they aren't coming back.
That was the #12 test desk.
@@gpwgpw555 Yeah, that was the old one. I would sometimes go inside to cover someone on vacation. We had a "temporary" test center using 2A cabinets.
You must be another old timer. We're disappearing fast. It seems like someone passes every other month. And not very old either. The business really changed. The smaller COs have no one working in them. The cable techs make the inside connections, at least they used to until the SMAZ frames. Good Luck.
@@robertcuminale1212 42 years as a switchman in Oklahoma City. I loved 37 years of it. In the last five years we became customer driven. meaning we did not fix anything unless customers reported trouble.
WOW, never knew any of this. Have a Wheatstone bridge in my collection that I got from a deceased estate for measuring resistors precisely, but the first Im hearing of these other people ie: as Jacobi and Christie. Once again much thanks for these stories.
Your videos on physics history are amazing Kathy, thanks.
Vitally necessary (for those of us into such topics), wonderfully researched and entertainingly delivered at a perfect pace. The highlighting of the documents to evidence what was said and when is a great touch. Superb :)
Thanks
Thanks for taking the time to share. Such a simple circuit but very important for the first precision or matched resistors . It all seems so simple and obvious now but in 1839 sourcing an electric charge,copper wire or other metal conductive wire took some scrounging as well as quantifying the electric charge s intensity and flow. The "Wheatstone" and Galv-meter led to the first calibration of tools to measure Volts Amperes and Ohms.
Thank you for this marvelously detailed video, I had time only for 5 or 6 minutes before skipping to the end. On mentioning " using Wheatstone bridge circuit for use with strain guages" to a Gloucester Engineering Manager years ago, It was mentioned he was associated with Gloucester and worked for Marconi .
I love your channel! its a breath of fresh air because most of these subjects are not discussed historically
Thanks for putting the fun into math and science. I watch all of your videos over and over. I have an interest in math and science but limited ability so that is why even though I have taken lots of college classes I do not work in the field and I have lots of bad memories in college with great suffering in tests and exams. But I watch your videos over and over and the joyous fun comes back to studying math and science because we see the human side to it.
Ms Kathy, your videos are very informative and well made. Thank you so much.
Hey, Jacobi didn't write that it was impossible that they had come up with the same idea independently, he wrote that it was impossible that Wheatstone "should have had the least notice of my instrument", implying that he was convinced that they HAD come up with the same idea independently.
Thanks for these videos!
And in the next sentence he praises Wheatstone for the wide variety of uses as a measuring tool that Wheatstone found for this device while himself only used it as a regulator. This is an extra argument for independent simultaneous discovery since they both created their device for different purposes.
@@christianbarnay2499 people at that time would choose politeness over direct confrontation to cope with public known figures stealing their ideas and decide to be the bigger person by attributing praise on the stealer not for stealing but in order to showing no hard feelings but they had internally recognised their own acheivements and felt it
@@kevindoom You can still politely criticize the attitude of someone, just like Cooke did when he clearly disapproved Wheatstone claiming their collaborative work as his own. When Jacobi says that Wheatstone and himself created the same instrument independently for different purposes (Jacobi needed a regulating device, Wheatstone needed a measuring device) there are no valid reasons to not believe him.
@@christianbarnay2499 i am the person that is on jacobis side in the first place
@@christianbarnay2499 whetstone was declaring that he independantly came up with it but in the exact same way the exact same way it was obvious of course Jacobi knew but he decided to deal with it politely
Kathy. Your great . Love your info
Thanks Sean.
You are a 'charismatic' educator / illuminator ... Thank you for sharing the 'back story' that is never shared in school.
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Thank you
Thank you for teaching us all.. GREAT!
We used a Wheatstone bridge to create a gas detector. Platinum wires were 2 legs of the Wheatstone bridge. One wire was enclosed in a glass tube and the other platinum wire was in a gas stream sampling from a vacuum pump hooked to a small hose. If methane or other volatile gas is introduced to that open wire, it raises the temperature and changes the resistance in the platinum wire. A chromatograph could then be built by injecting a set volume into a "column" of silica gel which slowed the heavy molecules down. A carrier gas was used to keep a steady flow over the detector filament. Helium could be used or dried air was commonly used in the more rudimentary instruments. First gas to come out is methane and then successively larger molecules. The bridge records the change in resistivity to a chart recorder (today it would be a data logger to display on a computer.) Very simple and important on a drill rig attempting to detect entrained gases in the drilling fluid, very robust and non-fragile.
I sit here and pinch myself because she is delivering such fantastic content.
just found your channel and anticipate impending productivity annihilation … still very pleased.
Love your lectures 😊. More power to you 😊😊😊
I love your content, knowledge and enthusiasm
Very well done, thank you for teaching physics in such an easy manner to comprehend.
Your videos are absolutely amazing.
Great videos Kathy, so informative and more accurate than what I learned in school! Louis
1:17 Micheal? "more accurate" indeed. 😈
Absolutely brilliant again, thanks!
The basic bridge arrangement can also be used with two inductors or two capacitors as the top or bottom two elements, and that makes a very sensitive way to compare capacitors or inductors. The circuit can also be used with a gain element like a tube or transistor to make a very accurate oscillator or filter. Hewlett-Packard's first product was an audio oscillator that used such a bridge.
So much research. It’s nice to get context on all these things which we now take for granted
I really liked listening to your lecture and as informative as you were, I was deeply happy with you as an endearingly sweet and quirky woman who reminded me of some of the most beloved in my family who, like you, always have something new for me to learn. Thank you, I look forward to watching more of your videos but now, as your subscriber.
Thanks for sharing your knowledges. Greetings from Ecuador😘
Good job! You are a good teacher!
Great! The history behind this ubiquitous concept that we use today in school lab to highly sophisticated electronic control system is very very fascinating.
Thank you.
So glad you liked it. Certainly fell down the rabbit hole with that one
In school i built a cryogenic fluid temperature measuring device based on the Wheatstone Bridge circuit.
Nice to hear the history and especially the evolution of thought. We all learn from each other....to be better.
Kudos for your excellent videos!
Amazing stuff, I have used Wheatstone bridges in some of my designs, and it is amazing to know a bit of history on it. Please make more videos :P.
Glad you liked it. Am working hard on new videos but it is always slower than I would wish. (I have about 80 videos on TH-cam for while you wait)
I worked as a Technician for a resistor company back in the 70's & 80's. We used our own factory built high speed testers and these testers were built with the wheatstone principles, but were far more complex. We had a decade resistor network that was set to the nominal value, two tolerance dials which set the plus and minus tolerance of the resistor under test. And finally a compensation pot that nullified internal resistance. Instead of two coaxial cables going to the test resistor, there were four and a compensation network was also applied to these cables. Then it really got complicated in that we had to test on the 60 cycle crossover. This was to keep any outside interference from the test. That crossover detection went to the logic circuit where it fed an "and" gate along with the bridge sample and the result "good" 1 or "bad" 0 went to a shift register. That's about it except that I did not mention that the sample signal is developed by a bi-latteral switch which is running at 60Hertz.
Thank you, what a find. Those who contributed to the sciences, thir story has to be told. Nicely done. Cheers!
I really love your channel!
OMG In America you have Edison who on account did innovations based on other inventors works, in the UK we have Wheatstone....What a story! Great video!!!!!!
This channel is so great
The last time I used a Wheatstone Bridge was as a college student 20 years ago something with strain gages and pressure transducers. With my soldering technique, it was a good thing I was going into mechanical engineering.
Very interesting development. Thanks for the history of electricity.
Thank you, Kathy.
We still have colorful scientists!
Well done. Thank you.
Very interesting how the facts don't seem to ever percolate to the surface. Well done. I'm a retired EE and son of an EE professor. Sadly, I do not find this at all surprising. I never heard of Tesla until I was 22, other than the magnetic field units, for instance.
Thanks for making the video.
You are welcome
I had not heard this history before. Great video
Yippie! And Thanks again for all the videos.
Glad you like them! Cheers, K
Whatever you call it, the Wheatstone bridge had a huge influence in accurately measuring the surface stress in mechanical parts using strain gauges (resistance varies with the tension applied to a metallic wire). Today, and for a very long time, strain gauges are sold in a Wheatstone bridge array which will automatically compensate for fluctuations due the resistance change brought on by the thermal expansion or contraction of the metal to which the strain gauge array is affixed.
It also applies to electrical meters, Ex: Western Electric 22A transmission test set.
8:25 Surely, Jacobi writes, "it is quite impossible that he should have had the least notice of my instrument"
I really enjoy your videos! They are superb.
Glad you like them!
Thank you so much for bringing this video to me.
Let the Lord bless you.
The long coil variable resistors were in common use into the 1950's. I have salvaged several old Fire Alarm systems that used them to account for different numbers of fire horns installed.
I think I must have found from somewhere (maybe a battery charging circuit?) a crude variable resistor, being a copper wire wound around a piece of asbestos board about 3in by 7in. The wiper was conected to a slider the top edge of the bread slice board and the feed to the first wire in the low position on the board. Interesting
Thanks for another great talk. Wheatstone also invented the ABC telegraph, which had the advantage of not needing expert telegraph operators at each end. Continued to be used till the 1930's in remote island locations without telegraph operators. Wheatstone seems to have been a bit of a dodgy character.
Interesting. Yeah, he was dodgy, I should have used that term, perfect to describe him IMHO
do you know if they were ever used in the old west?
Alexander Bain invented the ABC Telegraph (it’s in the video) - Wheatstone plagiarised it. He also discovered the earth battery that transatlantic telegraphy uses.
@@da8ish1 Think just in United Kingdom. Was used in the Highlands and Islands as no need for expert telegraphers which was the drawback of the Morse system as it was used in practice.
At 8:30 into the lecture I believe that there is a significant error pending your understanding of physics, but of the interaction between Jacobi and Wheatstone. Jacoby did not say that Wheatstone must have known about his instrument, in fact the opposite. he said it was "impossible the he should have had the least notice", which speaks to acknowledging that the idea was not stolen but done in parallel. He then goes on to in fact praise Wheatstone for discovering "a new method of measuring these current and of determining the different elements or constants, which enter into the analytical expressions, and on which depends the actions of any galvanic combination." He also acknowledges the sharing of valuable results from an yet published paper, again acknowledging Wheatstone.
Not the words of a wounded ego, I think.
Nor do I think negatively of your efforts here. The history was very well done.
I was glad to see that you did make it clear that Wheatstone’s bridge is balanced. I so dislike the misuse of the term by so many students who must get it from their teachers. Measuring zero current is so much easier than an actual current as the linearity of the measurement does not matter. Knowing the lost in translation and loss of references is interesting. Germanic use of references is different, or so I have been told, by those who fail to reference my work.
Hello Kathy, I'm not a total geek but I have to laugh hearing "Wheatstone Bridge" start my HVAC education in the 70's and soon after became a tech for Honeywell and offering classes on Honeywell products to contractors in the industry. The Wheatstone Bridge or reostat was a topic that was reviewed often . Thank you!
Great video. This is exactly the period of electrical history that I am interested in. (I'm working on a suspended coil galvanometer right now) Liked and Subbed.
Kath dishes the dirt on the convoluted electrical history. Love it.
Just wanted to say thanks for your Chanel for the information on science in regard of the history of the time, very informative 👍
You are welcome Paul. Glad you liked it.
I remember college classes that had Wheatstone bridge circuits, my impression is professors use this bridge for circuit analysis problems for homework and exams. But other than that, nobody uses it. Then out into the real world becoming involved with jobs that have strain gages, that's where I saw the value of the Wheatstone bridge. There is very very little change in resistance in the strain gage itself, probably not enough to reliably measure without the Wheatstone bridge. With the bridge, it becomes easy to measure (of course need reliable low level volt meter and stable excitation).
Strain gages can be fascinating considering they accurately measure stress in structures whether it be building I-beams, car frames, or force-moment balances.
8:27, the Jacobi quote you highlight says the opposite of what you state. Jacobi says it is improbable for Wheatstone to have known (had notice of) of his instrument, ie he thinks it was an independent invention, though later.
When studying electrical engineering, students barely have time to learn about the Wheatstone bridge and it's applications; hardly have time to learn about this history. However, now that Kathy has done all this legwork, EE students should watch this. In physics classes, much more history is provided in general physical principles like what are electrons doing, and who and how they figured this out.
You have a new subscriber, great talk
This is my 2nd video of this Kathy person. She's certainly got a good angle on tech, and she tells a good story! During the first video, the thought occurred, as my orbital muscles fatigued from tracking all the left and right motion across the bottom of the screen: would young Kathy be able to talk if someone tied her hands?
0:02 I got
Another great video. Thank you!
Thanks for the comment
Practical uses of the Wheatstone Bridge include load cells and strain gages. Force and dimension change are able to be computed after gluing resistors to materials that will undergo stress. Being able to solve the Wheatstone bridge means you can make your own load cells on the cheap.
Great talk
In your Ohm’s Law video, you mentioned that just as the unit of resistance, the ohm, is represented by the Greek letter omega (Ω), its reciprocal, the unit of conductance, the “mho,” is represented by an inverted omega. Some years ago, the unit of conductance was officially renamed the “siemens,” after the German inventor and founder of the Siemens company. In the 1960s I remember that the sensitivity of voltmeters was still expressed, at least in the US, in “micromhos.”
It's interesting to follow up this video with the article on Wheatstone in the Wikipedia. At first sight the article gives credit to Cooke and Christie.
Wheatstone was very prolific and worked on spectroscopy and acoustics as well.
Interesting you mentioned a means of testing low resistance values. . . Quite some years ago, I designed and built a 10 Amp "Earth Resistance" Tester. . .. Recently I had a failed Inverter, it tripped all its Battery feed breakers.. . I tested its DC input resistance with my "Earth Resistance" tester that uses an internal 12V battery and accurate 1 Ohm resistor, and found the DC input to that Inverter was down to 0.028 Ohm.. . . Years earlier there was a break on a UK-USA Cable, the special time fault locator was out of action, so the UK pulled out an old Wheastone Bridge and measured the fault o just of the USA coast.
Vielen Dank für diesen phantastischen Beitrag, fantastic job greetings from Germany.........
Danke
We used the principles for the wheat stone bridge to calibrate or certify many measurement tools but the most unique application was used in gas chromatography where using one leg measured heat loss from a gas sample stream while the other leg was maintained as a standard.
It's more than a paragraph, real time process instruments are complicated
Look up Siemens industrial gas chromatography, there are others but that name is mentioned
“Prof. Wheatstone has shown me an instrument, found on exactly the same principle as mine... Now it is quite impossible that he should have had the least notice of my instrument.”
Unless there is mistakes in the translation from German to English, the text suggested that Wheatstone has came up with the rheostat using Ohm law, and also that it is impossible for Wheatstone to see Jacobi' instrument prior.
A simple explanation why you could not find Jacobi's rheostat drawing could be he has never published it, since he thought the rheostat was insignificant comparing to the motor. If I am not mistaken Wheatstone could not have seen it. May be some other ideas was lifted by Wheatstone, but for the rheostat, knowing Ohm law he could come up with it by himself.
"A simple explanation why you could not find Jacobi's rheostat drawing could be he has never published it"
Such a drawing exists and he did publish it - check out the pinned comment.
Great Video! I first learned about the Wheatstone bridge in freshman physics: electricity and magnetism came right after mechanics and heat. Concerning Christie, sic transit gloria mundi. Christie was not the first nor the last to be unjustly forgotten by history because of unscrupulous self-promotors.
I've been to the Royal Society and read the minutes of the meeting where Wheatstone presented the bridge circuit to the other members. In the minutes he is quoted as saying that he would like to present to them, a circuit which was devised by, and given to him, (Wheatstone), by a Mr Christie.