Wikipedia:Reference desk/Archives/Science/2021 May 11

= May 11 =

What cause electrons move in the circuit even before redox reaction?
From Electric_battery, it says : Batteries are designed such that the energetically favorable redox reaction can occur only if electrons move through the external part of the circuit Rizosome (talk) 00:17, 11 May 2021 (UTC)
 * I've edited the text to read Batteries are designed such that the energetically favorable redox reaction can occur only if electrons are able to move through the external part of the circuit. Is that any clearer? nagualdesign 00:41, 11 May 2021 (UTC)
 * My edit was reverted with the summary, "The reaction requires actual movement, not the ability to move". I've changed the wording to Batteries are designed such that the energetically favorable redox reaction can occur only when electrons move through the external part of the circuit, although I think the previous wording was clearer. The reaction only occurs if the circuit is complete, allowing the flow of electrons. The language does rather confuse cause and effect. nagualdesign 01:45, 11 May 2021 (UTC)
 * Pinging . nagualdesign</b></b> 01:51, 11 May 2021 (UTC)
 * By the same logic, we can simplify "can occur only if" to "occurs only if": no current in the circuit, no redox reaction. (I think this simplification actually makes the sentence easier to comprehend.) --Lambiam 08:07, 11 May 2021 (UTC)
 * Electrons don't move if there isn't anything for them to move through. So, if you don't connect the wires between the anode and the cathode, the electrons can't move. They are not moving before the redox reaction, they are moving because of and at the same time as the redox reaction. However, no circuit, no movement, not redox. Now,, I need to ask you something, and I need you to answer honestly: do you still think batteries store electricity? --OuroborosCobra (talk) 01:19, 11 May 2021 (UTC)
 * It should also be noted that the electrons aren't leaving one place and building up in another. After it is done its work, the battery still has the same number of electrons as before.  What has changed is that those electrons have less potential energy than when they started.  They lost that potential energy as they traveled the electric circuit and returned to the battery.  Within the battery are substances where electrons tend to have high potential energy, and ones where they have low potential energy, and the electrons would naturally move between those two things, except they are prevented from doing so, and so need a path to get between those areas.  The battery needs two things to make this work 1) a completed circuit between the two electrodes and 2) a salt bridge between the two electrodes, which allows for positive ions to keep charge balanced and allow for all components inside the battery to remain electrically neutral (a build-up of charge would prevent the battery from doing anything).  -- Jayron <b style="color:#090">32</b> 12:13, 11 May 2021 (UTC)
 * In a defective battery, electrons might be able to move from the anode to the cathode without moving through the external circuit, which means they have an internal pathway. That is a bad thing; such a battery will not deliver the power it should and can overheat, causing an explosion or setting a fire. Batteries are designed such that this cannot happen; the only path for the electrons between the two poles is through the external circuit. --Lambiam 08:14, 11 May 2021 (UTC)


 * To be really pedantic, a redox reaction can occur in the battery before the circuit has been closed. The charge moved by the reaction will accumulate on the metal ends of the battery. Risking to confuse OP even more, any real battery can be modelled as a voltage source with some resistors, capacitors and inductors built in, and this capacitor has a really small capacity, so that only a small charge has to accumulate before the voltage on the battery reaches the voltage of the redox reaction. This makes the redox reaction energetically unfavourable, so the reaction stops. When we close the circuit, the charge can move, dropping the voltage and allowing the reaction to proceed. PiusImpavidus (talk) 09:14, 11 May 2021 (UTC)


 * The section Electric battery you quote refers you to Electrochemical cell as a 'main article', which in turn refers you further to Galvanic cell and Electrolytic cell as 'main articles' for respective sections. They explain quite clearly how the cell works, what reactions there are in cells and how they correlate to electrons movement.
 * However, the simple answer to your question is: it's an electric field, caused by a voltage (a difference of electric potentials between electrodes) which causes electrons to move (see Lorentz force).
 * If in turn you'd like to know what caused that voltage to appear, read more detailed and sophisticated answers by Jayron, Lambiam, PiusImpavidus et al. given above. --CiaPan (talk) 12:34, 11 May 2021 (UTC)

So without wire, electrons won't move between terminals hence electricity won't produce. Rizosome (talk) 00:15, 12 May 2021 (UTC)
 * Yes ...usually. However, a metallic wire is not always necessary to allow the current. There are other conductive substances, for example electrolytes – we can make a current through a liquid for electrolysis. If you build a really big battery, stacking a large number of cells, you'll be able to make a current with no wire, just through the air. The breakdown strength of air is about 3 MV/m (see Dielectric strength) so with a 30 kV source you can get an electric arc – an electrical breakdown through a visible, 1-centimeter gap. This is commonly used for welding. We can also let the current through other gases – see Neon lamp, Gas-filled tube and Neon sign for some examples. With enough voltage, or with additional heating, we can even get an electric current through vacuum — see Vacuum tubes, with CRT among them. --CiaPan (talk) 05:40, 12 May 2021 (UTC)

Can I say electric arc thing comes under wireless electricity? Rizosome (talk) 07:04, 12 May 2021 (UTC)
 * I never met a 'wireless electricity' term, so I suppose you can say it, but it probably won't get understood. Anyway, can you see any wire in a lightning? Or here: YouTube | Lugo SWR: Electrical arc from power lines. ...? --CiaPan (talk) 07:09, 12 May 2021 (UTC)
 * Wireless electricity is a thing; it was never widespread, but in the late 19th century, several large-scale tesla coils were used in a proof-of-concept to provide electricity without the use of wires. See Tesla Experimental Station for one that was in use in Colorado, and the Wardenclyffe Tower in New York which was intended for use in both power transmission and signal transmission.  Tesla's designs never went anywhere commercially, however, and wired power became the standard.   -- Jayron <b style="color:#090">32</b> 12:52, 12 May 2021 (UTC)
 * That was not about a 'wireless electicity' but rather 'wireless power transmission', as it is clearly stated in the lead paragraph of the article you link. To avoid a possible misunderstanding, we're not dicussing electric power transmission and distribution grid's problems here, from nuclear power plants down to electric sockets in walls of our houses; we talk about quite elementary physical phenomena. And from that point of view Tesla experiments were mainly application of electromagnetic fields generated by some electric circuit to induce current in another circuit; something we do all the time with multitude of transformers types (also with coreless air transformers, as depicted in the lede of Wireless power transfer). That has little to do with electric arc asked about. An arc is a group of phenomena related to electric current through ionized air. Certainly air in this state is not a wire, anyway it becomes a conductor, hence an arc has nothing to do with 'wireless electricity' (understood as wireless power transmission with EM fields). --CiaPan (talk) 15:17, 12 May 2021 (UTC)
 * Yes. You are correct.  -- Jayron <b style="color:#090">32</b> 17:26, 12 May 2021 (UTC)

Are you saying Wireless power transfer just a proper technical term for wireless electricity? Rizosome (talk) 05:10, 13 May 2021 (UTC)
 * It depends on what you mean by "wireless electricity". As you can see by reading the conversation between myself and CiaPan above, there's some uncertainty about what you meant by the term, and therefore what sort of thing you were looking for in an answer.  -- Jayron <b style="color:#090">32</b> 13:51, 13 May 2021 (UTC)

A pretty good summary of the oxygen supply problem
As with most crises, it's not the result of one problem or bottleneck, but many. Any other problem the article didn't mention? Imagine Reason (talk) 14:44, 11 May 2021 (UTC)
 * That article looks fairly comprehensive. -- Jayron <b style="color:#090">32</b> 15:56, 11 May 2021 (UTC)


 * All I've been able to read was: "You’ve reached your limit of free articles." Count Iblis (talk) 18:02, 11 May 2021 (UTC)
 * That is indeed a logistical problem. —Tamfang (talk) 00:52, 13 May 2021 (UTC)


 * Ultimately this is a problem of Logistics, which I think of as "Getting the right stuff in the right amount to the right place at the right time for the right price." It's usually complicated, involving many intermeshed factors. {The poster formerly known as 87.81.230.195} 2.125.73.196 (talk) 20:59, 11 May 2021 (UTC)


 * The article did not pay much attention to the inadequate, too often lackadaisical and sometimes downright harmful attitudes of several governments and the not well designed campaigns for advising people about safety practices, which made, and keep making, the crisis much worse than it could have been. --Lambiam 21:18, 11 May 2021 (UTC)