Wikipedia:Reference desk/Archives/Science/2014 October 28

= October 28 =

Space blanket - contra indication
I've red in the article "space blanket" in French that the contra indication of "space blanket" is a storm. I don't understand why is that. Before, I thought that the place to use it, it's only in storms and things like this. I'm wonder. 149.78.224.210 (talk) 00:33, 28 October 2014 (UTC)


 * If I'm reading your question correctly, you're wondering why a space blanket shouldn't be used during a storm. If that's so, it's due to the blanket being coated with a thin film of metal.  As metals conduct electricity, it would be a likely place for lightning to strike.  Dismas |(talk) 01:40, 28 October 2014 (UTC)
 * Not the way lightning works. It just traversed miles of air and a tiny bit of mylar isn't going to change it.  Pointy or height is what causes high electric fields, not metal.  --DHeyward (talk) 04:14, 28 October 2014 (UTC)
 * Several feet (a couple of meters) of conductive material may not make a difference to where the lightning bolt touches the ground, but it'll make a difference to where the electricity conducts to when it does. Not likely to be a big deal&mdash;unless those few feet are the difference between being seriously shocked and not. --174.88.134.249 (talk) 05:28, 28 October 2014 (UTC)
 * Is there a reliable source for that contra-indication? I would have expected the blanket to act like a Faraday cage.--Shantavira|feed me 10:42, 28 October 2014 (UTC)
 * I would expect nothing of the sort. Lightning would simply rip through the mylar. Justin15w (talk) 14:37, 28 October 2014 (UTC)
 * Plus that 5 to 6 feet tall column of extremely conductive mostly-salty-water might just take the strike first! SteveBaker (talk) 13:54, 29 October 2014 (UTC)


 * The reason has to be some other thing. The foil in a space blanket reflects heat from your body back at you, so you lose less heat than you otherwise would...it also traps warm air close to your body to reduce 'wind chill'.


 * The French article says absolutely nothing beyond that you shouldn't use it in a storm - and it has no references for that claim (which is usually a red flag!) - I couldn't find any such contra-indications in any of the places I searched for "How To" type stuff on storms or space blankets.


 * At this point, I'd ignore what the French article says - and perhaps re-ask this question on the talk page of the French article...or use the "View history" tab to figure out who added that statement to the article and ask them directly where they got that information from. SteveBaker (talk) 13:54, 29 October 2014 (UTC)

What is this a state?
In my country, in the USSR-Russia had always assumed that a state is the only the legitimacy of public statutus, so that a private deal which had not disobeying by the public rules is not been a private deal.

Did a state above all things is the legitimacy of private statutus or a state above all things is the legitimacy of public statutus?--Alex Sazonov (talk) 12:17, 28 October 2014 (UTC)
 * 1) This is the science desk. You may want to ask this at The Humanities Desk instead.  2) You seem to be asking about issues related to Power of a sovereign State to regulate Contracts between legal persons who are "private" (not arms of the state), be they persons or corporations.  Is that correct?  Your English is hard to follow.  -- Jayron  32  12:32, 28 October 2014 (UTC)
 * You understood me correctly, becouse all notariate (all notaries) in the USSR had always been a public (state)!--Alex Sazonov (talk) 13:31, 28 October 2014 (UTC)
 * In the USSR, a private deal which not had a public (state) approval, that is a private deal which is not been a notarial deal always was formed black market (shadow economy).--Alex Sazonov (talk) 15:00, 28 October 2014 (UTC)
 * Wikipedia has articles on black market, shadow economy, and handshake deal which may lead you places you are interested in learning about. -- Jayron  32  16:46, 28 October 2014 (UTC)
 * (Did) the cost of a private deal had be determine a nature of its statutus?--Alex Sazonov (talk) 17:35, 28 October 2014 (UTC)
 * This question does mean, (Did) the cost of a private deal had be determine a nature of statutus of this private deal?--Alex Sazonov (talk) 08:26, 29 October 2014 (UTC)

We can assume that in the legal right of Ancient Rome, all private deals between patricians and plebeians and foreigners were never been equal in their legal right and legal economic status, so all private deals between the patricians could be the legal nature of the impossibility of their challengeability. That is why in the USSR all notarially statutus had always been a public (state)!--Alex Sazonov (talk) 05:03, 29 October 2014 (UTC)
 * The main question of state doctrine of right of the USSR, Did a statutus of public (state) right been a statutus of international right?--Alex Sazonov (talk) 11:44, 29 October 2014 (UTC)


 * As noted above, this is the Science desk; unless you're talking about one of these meanings of "state", this is not the right forum - Reference_desk/Humanities has been suggested. -- Scray (talk) 14:40, 29 October 2014 (UTC)

state of matter
Matters exist in solid, liquid or gas state. What is the state of electrons, protons or neutrons? --Diwas Sawid (talk) 16:18, 28 October 2014 (UTC)
 * This question was asked in two locations. It arguably belongs here, but there are already answers at WP:RDM, so let's continue it there -- Jayron  32  16:45, 28 October 2014 (UTC)

This question was suggested to be asked here.Is it true that configuration of atoms ( made by elecctron ,proton etc ) determines state?? If so, In what form electron proton lies???Diwas Sawid (talk) 01:35, 29 October 2014 (UTC)
 * I think that in nature always be only electrons which in different substances always had a different names!--Alex Sazonov (talk) 06:11, 29 October 2014 (UTC)

Converting 5V USB to 12V?
I'm often annoyed at portable rechargeable consumer electronics (like portable speakers) requiring an AC adaptor to recharge. USB charging seems far more convenient as I'm always going to have a USB recharger nearby for my smartphone (at home, my car, the office). The main response I've gotten back is USB is limited to 5V, while their AC adaptor outputs 12V or 18V or what have you. So what does that mean? If it charged via USB, it would just be very slow? Or does the voltage difference just make it impossible? --76.168.132.112 (talk) 20:24, 28 October 2014 (UTC)
 * The issue is not just voltage - it's power. USB provides very little power, and can only provide it at a fixed DC voltage.  The power limitation is why the USB port can not be used as a universal charger; the voltage is an engineering detail that could be worked around with existing technology.
 * Electric power is very simply computed: it is voltage times current. The voltage (by itself) is not necessarily the limiting factor.
 * USB provides 5 volts, and very limited current: usually, 500 milliamps. This means that USB can not (usually) provide more than 2.5 watts of power.
 * The amount of power is going to dictate how fast your battery charges; how bright your screen gets; how large an electric motor you can drive.
 * But there are other details. Power must be provided at a voltage that the device can handle.  If the voltage is too low, the device won't even work - whether it's a charger on an appliance.  If the voltage is too high, the device may be damaged.
 * Wasteful energy losses - like heat - are primarily determined by current - so lowering the current usually lowers losses. Consider a power supply that provides 10 watts at 18 volts.  (P = V*I), so the device draws a little more than half an ampere.  The same amount of power could be delivered by low current at very high voltage - say, a million volts driving ten microamps - but at some point, the voltage levels become unsafe for use around humans.  High voltages can cause electrocution; very high voltage electricity can leap across air gaps, zap through wire insulation, and so on.  At the opposite extreme, the same amount of power could be delivered by very low voltage and very high current - say, a million amps, driven by 10 microvolts - but resistive heating means that the wires would waste so much energy (as heat) that their insulation catches fire!  This is to say nothing of the impracticality of building such a power-supply.
 * Engineers make trade-offs to make sure that the right amount of power gets to the device, at the correct voltage and current - balancing safety against usability and convenience. A few standards have formed; consumer-devices that are mass-produced are designed to operate within these standards.  Engineering practicality means that it is easier, safer, and more efficient to provide higher power using higher voltage than USB can provide.  But the power still has to come from somewhere - even if the voltage is converted!  Until the device itself needs less power than the USB port can provide, trying to charge it at 5 volts isn't an option.  Even if you boosted to 12 volts, you wouldn't get energy for free!
 * Nimur (talk) 21:03, 28 October 2014 (UTC)


 * To recharge a battery, you need a little more voltage than the battery itself provides...how much more depends on the battery technology. So you can certainly recharge a typical 1.5 volt AA or AAA cell - or even two or three of them in series - using USB.  The current (amperage) limitations of USB will limit the speed that it recharges.
 * So if you need 12 volts to recharge something, then USB (by itself) won't cut it. There are ways to add some circuitry to increase the voltage from 5v to 12v - but the amount of power available (volts times amps) stays the same, or a little worse.   So going up from 5v to 12v would decrease the amps to less than half...possibly much less than half depending on the efficiency of the voltage conversion circuitry.   Generally, it's just easier to get a separate charger.  SteveBaker (talk) 13:39, 29 October 2014 (UTC)

mixing medicine liquid with another liquid
what is the reason of the mixing a liquid medicine in another liquid (like saline), while we can inject only the medicine liquid? 149.78.224.210 (talk) 23:57, 28 October 2014 (UTC)
 * Because medicines are carefully calibrated at certain concentrations. Pharmacodynamics is a tricky thing, and changes to how drugs are formulated and delivered can have large effects on things like their effectiveness and their toxicity.  For that reason, procedures and formulas are created, which should always be followed, because the people who created the protocols know what they are doing, and you probably don't.  -- Jayron  32  11:12, 29 October 2014 (UTC)

What is the difference between syrup and elixir?
149.78.224.210 (talk) 23:58, 28 October 2014 (UTC)


 * Read the articles you already linked, and decide for yourself. -- Jayron  32  11:13, 29 October 2014 (UTC)