Is ohms law in trouble - Page 1
Forum section: electronics / general

author: John Heath
author_rank: Frequent Contributor
timestamp: December 26, 2017, 05:15:20 pm
content: A Klaus von Klitzing has been messing with our ohms law and I do not like it. Surely he as better things to do. Unfortunately they gave him a Nobel prize so it looks we are stuck with it. What I would like to know is what is he getting at in simple layman's terms so that the rest of us can understand.What I have found so far armed with Google.We have a 25.813 K resistor in nature and that is it. You may not have a 26 K nor 28 K only 25.813 K.For my 2 cents I have a roll of 10 K resistors that can be mailed to Mr Kiltzing.The heart of it has something to do with the Hall effect on a very thin sheet of copper boiled down to h/e^2 = 25.813 ohms.Mr Kiltzing feels more comfortable talking to aliens about this. We educated him , we gave him a Nobel prize , what did the aliens do zip nada zero. Leaving this aside Mr Kiltzing explaining why we can only have a 25.813 K resistor.If anyone can translate this so that the rest of us can understand please do so.

author: Dr. Frank
author_rank: Super Contributor
timestamp: December 26, 2017, 06:28:28 pm
content: Really nice interview.Fortunately, he didn't get the Nobel Price for literature; his English sounds like Alien language.The nice Klitzing Prototype Ohm of 25812.8.... Ohm is made by Burster...And the Quantum Klitzing Ohm will have an exact value of about 25812.80746 Ohm from 20th May 2019 onwards.Frank

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: December 26, 2017, 06:45:13 pm
content: So the video did not claim that one couldnothave resistors of values other than one kiltzing undernormalcircumstances. There seems to be necessary a very strong magnetic field. The field strength was not mentioned, but if it dimmed the lights of Grenoble it must have been strong indeed.Does not seem likely, then, that we will be measuring these resistors in hobby labs. Its another JJ-like technology.The presence of aliens means that you are not to take it *too* seriously. They only come down to visit earth under properly humorous circumstances.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 26, 2017, 06:48:37 pm
content: Ohms law in its original form applies to metals, while the quantum hall effect is found in special semiconductor samples at low temperature and strong magnetic fields. So the two are not much in touch with each other.It's a little like polar bears not eating penguins.Quantum hall effect is a strict 4 wire resistance you get in special samples / chips at low temperature and a strong magnetic field. One sends a small current in a suitable range through 2 contacts and measure (with no current flowing) a small voltage between 2 other contacts. In a limited current range the ratio of voltage to current is that special resistance or a multiple.To make this happen the temperature needs to be very low (e.g. He temperatures) and the probe very small and from a semiconductor material with very high electron mobility. It is kind of similar to a HEMT transistors with 4 drain / source contacts.The special thing is that this resistance is extremely accurate and the same number in all such samples. So it is a near perfect primary standard for metrology purpose. However due to the special requirements it is not that practical in every days use - the current is very limited and the voltage small.The quantum resistance is no a thread to Ohms law - if at all it could show that the current quantum mechanics is somehow off a little. With quantum hall, Josephson voltage and counting electrons, there are three effects that are liked by h/e^2 and frequency. So far the circle is consistent - so it is a great success for quantum mechanics.

author: John Heath
author_rank: Frequent Contributor
timestamp: December 26, 2017, 07:50:22 pm
content: Great responses. I knew if I dragged the quantum hall effect into the EEVblog we would get to the bottom of it.If we say Quantum then the full weight of quantum mechanics must be applied worts and all. If He makes a measurement of 25.813 K can he also know where he made this measurement or if he knows where can he also measure 25.813 K ? Apologies I could not resist.Yes indeed if the magnet field is drawing enough power to slow street cars down then it is a very strong magnetic field. My confusion is over the measurement of 25.813 K regardless of length , width or material being used for the Q hall effect? Does he mean a calculated resistance per electron therefore the length or width are not relevant?

author: Macbeth
author_rank: Super Contributor
timestamp: December 26, 2017, 08:05:43 pm
content: I think I've got one of these resistors in the back of my parts drawer - reading the lengthy chain of colour codes it purports to be 25812.98168142762768702549980273195633231220734657508139

author: John Heath
author_rank: Frequent Contributor
timestamp: December 26, 2017, 08:46:24 pm
content: I have that as 25812.98168142762768702549980273195633231220734657508138 not 25812.98168142762768702549980273195633231220734657508139 . don's mean to split hairs , I'm just saying.

author: Macbeth
author_rank: Super Contributor
timestamp: December 26, 2017, 08:51:55 pm
content: Yeah, that last colour band it's kind of off-white, it could by greyBut I think I'm righthttp://www.kaero.wz.cz/jokes.htmlscroll down to "J and K after redefinition of SI"

author: Bud
author_rank: Super Contributor
timestamp: December 26, 2017, 09:00:44 pm
content: Quote from: John Heath on December 26, 2017, 05:15:20 pmYes you can. Just ask a Shenzhen factory to make you one. They can even supply a custom made multimeter along, which will measure it. And being real professionals, they will even ask you if you want a fake receipt for the Customs.

author: Electro Detective
author_rank: Super Contributor
timestamp: December 26, 2017, 10:17:14 pm
content: Quote from: John Heath on December 26, 2017, 08:46:24 pmHow many of the last digits get affected by the soldering process, temperature, time, solder type, flux, and interaction with the PCB materials/tracks etcand whether using Hakko or Weller irons vs TooHungLo knockoffs25812.98168142762768702549980273195633231220734657? ? ? ? ? ?

author: John Heath
author_rank: Frequent Contributor
timestamp: December 26, 2017, 10:21:57 pm
content: I stand corrected it is 25812.98168142762768702549980273195633231220734657508139Josephson constant is interesting 483 597.9 x 10^9 Hz. That puppy ain't no weeny. 483 THz is red light. This being said I am not filled with a warm feeling of understanding. Both the Q hall effect 25.813 K constant and the Josephson red photon constant are not revealing a light at the end of the tunnel. What does one do with this information to anchor your boat for a better understanding?

author: texaspyro
author_rank: Super Contributor
timestamp: December 26, 2017, 10:24:05 pm
content: Quote from: RandallMcRee on December 26, 2017, 06:45:13 pmAnd they come swinging a big-ass probe...

author: John Heath
author_rank: Frequent Contributor
timestamp: December 27, 2017, 02:41:40 am
content: Quote from: Kleinstein on December 26, 2017, 06:48:37 pmBears eating penguins , that is like the cat in a box that could be alive and dead. Leaves the penguins alone and the cats for that matter.I have a carbon resistor and a wire resistor of the same size very cold in a magnetic field. They are unlikely to measure the same resistance. This is the part that I do not understand. How does he make the resistance measurement that is independent of size and type of material. I am sure there is a simple answer but in the video he does not specify. It is hard to hang your hat on this one without the details. What did he measure and from that how did he calculate 25.8 K ? I want to share in the success of QM but without the details for the intuitive understanding it is just words without the beef. The video is entertaining and informative but a little patronizing in its lack of details.

author: wraper
author_rank: Unknown
timestamp: December 27, 2017, 03:19:25 am
content: Quote from: John Heath on December 27, 2017, 02:41:40 amhttp://www.bourbaphy.fr/klitzing.pdf

author: John Heath
author_rank: Frequent Contributor
timestamp: December 27, 2017, 03:32:05 am
content: Quote from: wraper on December 27, 2017, 03:19:25 amNow we are talking. Nice link and thank you.

author: guenthert
author_rank: Frequent Contributor
timestamp: January 31, 2018, 09:27:46 am
content: I just noticed that WolframAlpha offers resistor networks for a given resitance. So you can build your own 1Klitzing resistor, since you can't get it on fleebay.http://www.wolframalpha.com/input/?i=h%2Fe%5E2&rawformassumption=%7B%22MC%22,+%22h%2Fe%5E2%22%7D+-%3E+%7B%22Unit%22%7D&rawformassumption=%22UnitClash%22+-%3E+%7B%22h%22,+%7B%22PlanckConstant%22%7D%7D

author: John Heath
author_rank: Frequent Contributor
timestamp: January 31, 2018, 04:25:41 pm
content: I am liking the 33K in parallel with a 100 K with 1 K in series. That is .003 percent of the Klizing resistor. If we consider the Klizing resistor to be 1 not 28 K then what would the other units such as voltage inductance capacity look like in the new universal standard? If aliens were to visit us it would be nice if we were using universal SI standards so they do not think we fell out of a tree yesterday.I use Wolframapha and it has an odd way of knowing what you want and going the 9 yards to deliver. It must be sophisticated software that goes beyond math solving by looking for meaning.