Guy Rixon Posted November 22, 2020 Share Posted November 22, 2020 29 minutes ago, Northroader said: If I went into the ironmongers and asked for a pack of ytterbium, what could I do with it? (Yes, besides that) Very little on a conventional workbench. It's a gamma source, and also used in ultra-high-stability clocks, the ones you get if a caesium fountain just won't cut it. I thought it was one of the elements used in posh magnets, but Wikipedia doesn't mention that. 4 3 Link to post Share on other sites More sharing options...
RMweb Premium TheQ Posted November 22, 2020 RMweb Premium Share Posted November 22, 2020 NPL use a Josephson Junction to measure DC voltage, this is traceable to a Quantum standard, we send our travelling voltage standard there every few months, by special taxi, powered by battery at all times, to get our voltage standard reference values. The results for 10V will report something like 9.999,995,37V This is then compared to our voltage reference stack of 10 of these units, to get our value.. Our travelling unit may also go to the USA or Germany to compare against their references. Equally we get in both other labs reference units for comparison and lower level labs reference units for commercial use. When I'm measuring a voltage to 0.1parts in a million, the equipment will detect a car going past outside to the company rear car park, or a human walking up to the door of the lab 10ft away. 1 5 Link to post Share on other sites More sharing options...
Nearholmer Posted November 22, 2020 Share Posted November 22, 2020 28 minutes ago, Donw said: Your battery may shove a few electrons into the ground and pull some more out of the ground elsewhere but the ground current flows are to do with balancing the sum of all those actions there is no distinct flow through the ground driven by your battery . The general mass of earth is no different in that respect from any other conductor in which multiple currents might be flowing between multiple sources and multiple loads. My quip about "getting home" related to static electricity BTW, and I still hold that one day it all will. As a sort of a BTW, I can't think of any traction power supply systems that use the general mass of earth as a conductor, although a few very early experimental ones did, so by definition all or any traction currents flowing via the general mass of earth are stray currents - they are flowing outside of their designed path. 6 Link to post Share on other sites More sharing options...
RMweb Premium Compound2632 Posted November 22, 2020 RMweb Premium Share Posted November 22, 2020 1 hour ago, Guy Rixon said: and also used in ultra-high-stability clocks, the ones you get if a caesium fountain just won't cut it. I'm glad you know that; not many people do. 1 hour ago, TheQ said: NPL use a Josephson Junction to measure DC voltage, this is traceable to a Quantum standard, we send our travelling voltage standard there every few months, by special taxi, powered by battery at all times, to get our voltage standard reference values. The results for 10V will report something like 9.999,995,37V This is then compared to our voltage reference stack of 10 of these units, to get our value.. Our travelling unit may also go to the USA or Germany to compare against their references. Equally we get in both other labs reference units for comparison and lower level labs reference units for commercial use. When I'm measuring a voltage to 0.1parts in a million, the equipment will detect a car going past outside to the company rear car park, or a human walking up to the door of the lab 10ft away. Ah the joys of intercomparisons. 1 Link to post Share on other sites More sharing options...
RMweb Premium Andy Hayter Posted November 22, 2020 RMweb Premium Share Posted November 22, 2020 6 hours ago, Compound2632 said: RE: Electrons and not having seen the same one twice You wouldn't; they're all identical. That's the trouble with you supremacist white folk; you see something that you are not familiar with and "they all look the same": Residents of the Indian Sub-Continent Chinese (including Japanese, Vietnamese etc. Coloured people from the US Electrons. WE ELECTRONS ARE ALL INDIVIDUAL. No more anti-electron speak please. 1 7 Link to post Share on other sites More sharing options...
RMweb Premium Compound2632 Posted November 22, 2020 RMweb Premium Share Posted November 22, 2020 27 minutes ago, Andy Hayter said: WE ELECTRONS ARE ALL INDIVIDUAL. No more anti-electron speak please. Nah, that's all spin. 2 5 Link to post Share on other sites More sharing options...
Caley Jim Posted November 22, 2020 Share Posted November 22, 2020 I hope we aren't going to be examined on this as you lost me several posts ago! Jim 2 1 2 1 Link to post Share on other sites More sharing options...
RMweb Premium St Enodoc Posted November 22, 2020 RMweb Premium Share Posted November 22, 2020 18 minutes ago, Caley Jim said: I hope we aren't going to be examined on this as you lost me several posts ago! Jim Me too - and I did read the whole of "A Brief History of Time" once (only once...). 3 1 Link to post Share on other sites More sharing options...
Canal Digger Posted November 22, 2020 Share Posted November 22, 2020 3 hours ago, Donw said: All of which only proves my point in the earth currents all get mixed together and some do stray. Yes they all balance out but talking of it all getting home missed the point. Your battery may shove a few electrons into the ground and pull some more out of the ground elsewhere but the ground current flows are to do with balancing the sum of all those actions there is no distinct flow through the ground driven by your battery . The effects of large power flows may seem more evident but are not exactly matching the current causing them. I know a bit about stray currents we had trouble with them with lead sheathed cables. It works rather like pooled railway wagons you might ship a wagon load from britol to leeds the wagon doesn't come back it gets sent to donacaster with another load however at times too many wagons are at one place and too few somewhere else so a balancing load of empties might be necessary. Don Recalling my days spent studying for my C&G/ BTEC (that dates me!) Electrical Technicians, Kirchoff's II (ie Voltage) Law states that the sum of the EMFs (Electro Motive Forces) must equal the sum of the PDs (Potential Differences) in a given circuit. All those wasted days (I never want to see another transistor again, please!), I never used any of the theory in practice. Sorry about the (()))s 3 Link to post Share on other sites More sharing options...
RMweb Premium Compound2632 Posted November 22, 2020 RMweb Premium Share Posted November 22, 2020 I like the pizza model: The pizzeria is the cell, providing energy - pizzas - which the electrons - pizza delivery persons on scooters - transport around the circuit - the road - to keep the party (the lamp) well lit up. Energy is transferred but charge is conserved - the current (flow of delivery scooterists) is the same everywhere in the circuit. 3 Link to post Share on other sites More sharing options...
Canal Digger Posted November 22, 2020 Share Posted November 22, 2020 3 hours ago, Nearholmer said: Be useful for the rivets in fork ‘andles, I reckon. Rivets in four candles?? At the risk of going off topic, the balsa wood used for the Two Ronnies Folk Dancers Sketch came from the model shop that was in Fairfax St in Bristol 2 1 2 1 2 Link to post Share on other sites More sharing options...
Nearholmer Posted November 22, 2020 Share Posted November 22, 2020 No matter how many times ........ 4 3 Link to post Share on other sites More sharing options...
RMweb Gold Donw Posted November 22, 2020 RMweb Gold Share Posted November 22, 2020 52 minutes ago, Canal Digger said: Recalling my days spent studying for my C&G/ BTEC (that dates me!) Electrical Technicians, Kirchoff's II (ie Voltage) Law states that the sum of the EMFs (Electro Motive Forces) must equal the sum of the PDs (Potential Differences) in a given circuit. All those wasted days (I never want to see another transistor again, please!), I never used any of the theory in practice. Sorry about the (()))s Yes this is tue except within the earth so much is going on that you could never identify them. You get a thunderstorm and wham one hell of a whack of current hits some spot on earth and the extra potential starts to try and even out. By the time you measured the potential of a few places it will all be changed you would never be able to manage to actually balance them all. Just accept that by natural forces they will be trying to achieve a balance but other natural forces will be causing disruptions and we cause some too. 1 Link to post Share on other sites More sharing options...
monkeysarefun Posted November 22, 2020 Share Posted November 22, 2020 1 hour ago, Nearholmer said: No matter how many times ........ Maybe its because I'm Australian but I've never understood the punchline. 3 Link to post Share on other sites More sharing options...
Caley Jim Posted November 22, 2020 Share Posted November 22, 2020 2 hours ago, Compound2632 said: I like the pizza model: Do you mean this one? 2MM scale NG by Mark Fielder. Jim 8 1 Link to post Share on other sites More sharing options...
RMweb Gold Regularity Posted November 22, 2020 RMweb Gold Share Posted November 22, 2020 47 minutes ago, monkeysarefun said: Maybe its because I'm Australian but I've never understood the punchline. Fork handles. Dropped “H”, gives “Fork ‘andles,” homophonic to four candles. If you mean the very weak bit at the end, then “bill hooks” is supposed to put the word “b0ll0cks” into the frame. 1 1 Link to post Share on other sites More sharing options...
RMweb Gold Regularity Posted November 23, 2020 RMweb Gold Share Posted November 23, 2020 4 hours ago, Andy Hayter said: No more anti-electron speak please. That would be a positron. 1 2 Link to post Share on other sites More sharing options...
monkeysarefun Posted November 23, 2020 Share Posted November 23, 2020 26 minutes ago, Regularity said: Fork handles. Dropped “H”, gives “Fork ‘andles,” homophonic to four candles. If you mean the very weak bit at the end, then “bill hooks” is supposed to put the word “b0ll0cks” into the frame. Yes, the last bit about bill hooks. B0llocks... I see, I've obviously been trying to read too much into it. 2 Link to post Share on other sites More sharing options...
Caley Jim Posted November 23, 2020 Share Posted November 23, 2020 9 hours ago, Regularity said: That would be a positron. My grandson told me that his chemistry teacher said that none of these particles actually exist! Jim 4 1 Link to post Share on other sites More sharing options...
RMweb Gold Regularity Posted November 23, 2020 RMweb Gold Share Posted November 23, 2020 (edited) 2 hours ago, Caley Jim said: My grandson told me that his chemistry teacher said that none of these particles actually exist! Jim Ah, that’s the difference between chemists and physicists: one of of those groups has more fun... Just a thought, but your grandson’s chemistry teacher appears to be anti-antimatter, and as we know from grammar and maths, two negatives make a positive, so that means these particles do exist... Edited November 23, 2020 by Regularity Addendum 2 3 Link to post Share on other sites More sharing options...
Canal Digger Posted November 23, 2020 Share Posted November 23, 2020 I have a friend (he may be a member of this forum?) who denies the electron flow theory, instead smoke somehow 'carries the power' along the conductor in very thin bore tubes, the proof being that it sometimes escapes .... 2 1 3 Link to post Share on other sites More sharing options...
RMweb Gold Regularity Posted November 23, 2020 RMweb Gold Share Posted November 23, 2020 11 hours ago, monkeysarefun said: Yes, the last bit about bill hooks. B0llocks... I see, I've obviously been trying to read too much into it. Possibly because you hoped (against the evidence) that the final bit was actually funny. 2 Link to post Share on other sites More sharing options...
RMweb Gold Regularity Posted November 23, 2020 RMweb Gold Share Posted November 23, 2020 14 hours ago, Compound2632 said: I like the pizza model: I prefer the Buddha pizza myself. ”Make me one with everything.” 6 Link to post Share on other sites More sharing options...
monkeysarefun Posted November 23, 2020 Share Posted November 23, 2020 34 minutes ago, Regularity said: I prefer the Buddha pizza myself. ”Make me one with everything.” You can get them from the Deli Lhama. 5 5 Link to post Share on other sites More sharing options...
Edwardian Posted November 23, 2020 Author Share Posted November 23, 2020 13 hours ago, Regularity said: ... put .... “b0ll0cks” into the frame. Not an idea I can contemplate without a feeling of queasiness. 2 3 Link to post Share on other sites More sharing options...
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