Externet

Thanks again, Melvin. "the Al/Cu cell is that the amperage is very low" -->Isn't that more a function of the electrodes area? What am unhappy with Cu/Al is that would yield too low voltage. "if you used a more alkaline solution" -->No, the whole thing is about seawater. "you could be able to make a crude cell that could just be replenished with acid" -->Am not trying to make a cell on my workbench; it is more like trying to learn what voltage would yield dipping a 4'x8' Mg and a 4'x8' stainless steel plates in the real sea. Yes, that big. I cannot forecast results from the electromotive series and galvanic series tables, I even do not know why are they different nor which one to use and how.

Thanks, Melvin. The point is not the economics of the cell construction at all. The Mg-graphite on link above seems to be the most convenient and effective way to produce electricity (~1.5V) from seawater and am happy with it. These cells are used in open sea bouys that provide telemetry for years between servicing, at the expense of Mg metal as a 'fuel', and am happy with that. Cost of Mg is peanuts compared to moving a ship and crew 2000 miles for servicing shorter duration cells. My lack of understanding is the (chosen?) use of dissolved oxygen which is present in limited amounts on the electrolyte that has (apparently to me) much higher availability of Cl, Na ions to engineer a reaction. Let me put in other words. Using Mg; what other energic electrode instead of graphite coud interact with the ions instead of oxygen to produce long life electricity ? For sure developers of such cell had it very thought. I just do not get it. Another cell could be made with Al and Cu electrodes (none being pure sodium), but the generated potential is only ~0.3 V and does use Cl and Na ions for the reaction, not oxygen. So, could the voltage be raised to nearly 1 Volt and use the ions ?

Hello. I do not get it; can anyone explain on layman terms ? This reaction on a Mg - C cell uses the dissolved oxygen : http://www-odp.tamu.edu/publications/191_IR/chap_03/c3_5.htm From the galvanic series table Mg and C are at the extremes (I assume to yield maximum potential difference): http://www.corrosion-doctors.org/Definitions/galvanic-series.htm ---> Why are the most abundant Cl and Na ions not considered better to be used for the reaction ?

Do you really believe the police in such risky country can be alerted by the gadget ? Do you think the perpetrators will leave your technobra on you? Perhaps a different applicable strategy applies : http://www.wimp-software.co.uk/ http://forum.xda-developers.com/showthread.php?t=340667 http://www.luisespinosa.com/trackme_eng.html Miguel

Whaaaat ???

How does the device briefly shown here inside a cabinet works ? http://www.youtube.com/watch?v=V1IfzVrNqtU&feature=related The output seems to be a detergent injected with microbubbles. How does the mixing produces the bubbles so small ?

Found something, but still do not know what compounds are they Niopen http://www.alibaba.com/product/ua103664211-103455883-0/Foam_agents_for_foamed_concrete_making_NIOPEN_and_BIOPEN.html and OBSH http://www.alibaba.com/product-gs/237089510/OBSH_foaming_agent.html Miguel

Hi. My father once told me that in those days of early automobiles with fail-prone windshield wipers, applying a raw potato cut surface to the glass exterior forms a sheet of water allowing decent vision; was a common resource then, and it is confirmed to work well. What goes on and what chemical from the potato is the acting agent, and equivalent 'modern' chemicals? Miguel

Hello Paul. The wires can be made/insulated/routed to not short circuit. Or, if you prefer, insert a car cigarette lighter element at the end inside the handle. That will really put you cooking... Same safe low voltage (12V or less for less amount of heat) http://www.coolest-gadgets.com/20080716/heat-me-usb-heated-stirrer/ http://www.surplusandoutdoors.com/ishop/877/shopscr3059.html Miguel

Hi. Seen variations of your post in several places. Your whisker, http://virtue.win.mofcom.gov.cn/www/23%5Cvirtue%5Cimg%5C2008829174856.jpg with a metallic tubular handle could host a few automotive light bulbs inside. (there is some cylindrical ones that could well fit) http://www.autoguide.net/apf/images/products/engineparts/5y89947950lhi.jpg Solder the connections, bring the wires out at the end of the handle, and being powered by 12V, pose little risk of electrical shocks, will transmit their heat easily trough their glass to the handle; and the supply is not a hard thing to find (a spare laptop supply works) Then, the whisker can be held with an oven mitt. Miguel

Hello. Resistive wire is what you want; as the one in your bread toaster, the one that glows red. Wrapping the tubular handle with a heat conducting - electricity insulator material and a few turns of the wire will warm thing up. Such wire is also used in hair dryers, electric blankets... Depending if you want to warm up your hand or the stirrer, place some thermal insulation accordingly. Apply only the needed voltage to obtain the desired temperature depending on how long/thick is the wire. I do not think that wire is the proper one. Nichrome is preferred for your application. Miguel

Hello. Do you know of any inorganic compound in powder form that becomes gas when triggered by an 'stimulus' like light, microwaves, heat... Like every particle of the powder release or turn to gas ? I want to make bubbles, megazillions of them... How is styrofoam made? Is it by mixing two chemicals or by external stimulus ?

Hi. Itching is not a painful sensation, as pinching, or piercing, or a burn... Scratching provides relief, and pleasure. If some of you have had serious/intense skin complications; will understand scratching can get pleasant to extremes. What goes on with the causes of itching ? Not only related to insect bites, but the sporadic skin manifestation, either by a recognizable presence of a microbe or none. How come scratching provides pleasure? An 'evolutionary' thought of scratching providing dissemination of microorganisms under fingernails... is that real ? Let me say it different... Do itching causers provide chemical pleasure to bearers so scratching promotes dissemination ? Would an analysis of material under the fingernails show spores or something that proves scratching is a transmission method of itching causing microorganisms ? Sorry about my poor English Miguel

A 3 blade turbine, and a 12 blade turbine; being both the same diameter http://econewmexico.com/system/files/images/wind-turbine-wind-mill.jpg Which one is more efficient, can produce more power ? There has to be other variables as blade pitch, blades area, speed... even temperature... What formula applies to find out the power that can be extracted from a given wind speed ? Asking this because a large count blades turbine presents a larger blockage and reaction to wind than a 3 bladed one as the modern turbines are designed. There has too be other economical and construction factors involved to choose one or the other, but as amount of wind capture, one has clear advantage.

Thanks, Klaynos. It was more qualitative and behavioral than specific; but can put some simple generic figures if helps. A 10cm x 1cm x 1cm magnet bar suspended in space produces a 'small' amount of magnetic field at a point X distant 100cm perpendicular from its center. Its lines of force 'exit/enter' the ends of the bar magnet describing a certain undisturbed and smooth typical curvature. Its lines of force reach point X faintly being that much distant. What manipulation of the magnet / lines of force could increase the magnitude of the magnetic field at X. See the figure here: http://www.acesinternational.org/images/32NE0014.gif How 'smooth' the lines of force are sketched entering/exiting the ends of the magnet. See : http://www.bbc.co.uk/schools/ks3bitesize/science/images/sci_dia_75.gif how the lines of force are exiting/entering almost perpendicular to the magnet end because of the repulsive field nearby. Is that sharper bend yielding/projecting more lines of force at X ? It is basic that I express properly my question; please let me know if it needs more improvement. Miguel

Obviously, the post above has to be very poorly expressed and unclear to receive no responses. Am sorry. Allow me to ask from a totally different angle: What magnet shape would project its lines of force further away? A bar, a horseshoe, a plate, a cube, a slitted, a sphere, ...

A plain bar magnet --------------------------------------------------------------------------------- N................................................................................................S --------------------------------------------------------------------------------- above, will produce a given field at point x below : ................................................X If the ends of the magnet body are bifurcated by slits "===" : --------------------------------------------------------------------------------- N.................................................................................................S ===......................................................................................=== N.................................................................................................S ---------------------------------------------------------------------------------- Each end will have two same polar N-N , and S-S. That will make the lines of force at the ends, to diverge, by repulsion to each other. Will the same point X then experience a larger, equal or greater field ? ..................................................X In other words, will the magnetic field reach farther or be stronger by slitting the ends of a bar magnet? [ignore the dots on the sketch] Miguel

Can solar winds carry off a polyethylene bag filled with air ?

7.7 x 10E13 litres; not considering temperature change

If I understand well; 1) the attraction will be greater between two identical magnets. 2)Attraction will be larger to a 'larger' steel plate than to a cube, as the amount of lines of force conveyed by the plate will be larger.

One litre of earth sea level atmospheric air, if taken to the moon surface and released into a non elastic polyethylene bag as large as needed, would occupy what volume ?

Perhaps this could be in general physics, but here I go... What is the voltage generated using Aluminium and copper Carbon and magnesium Aluminium and magnesium Copper and magnesium as electrodes in 3.4% ClNa ? Where is a table that gives the values that its differential potentials determines the voltage generated ? -if that is how I remember it works- Miguel Merged post follows: Consecutive posts mergedNever mind... found it: http://www.corrosionsource.com/handbook/galv_series.htm

Hi. Similar but not exact, yes. No problem, it was properly responded. Thanks. Opened another thread due the response rationale; poor retention and wicking effect of nylon, availability of material was getting complex, and decided to make things simple to obtain, plus a change in hardware from exposure to sunlight into shade. Miguel

I learned in elementary school 1 Kilogram equals 1 litre or 1Kcc of water; 1 gram equals 1 CC of water. Merged post follows: Consecutive posts merged The metre was defined first. Measured the distance from a pole to equator, divided by 10 million. They got pretty close with the technology available then. Derived from it, the litre (0.1m x 0.1m x 0.1m) and the ton (1m x 1m x 1m of water). Speed derives from it, also force, acceleration and many others. The definition of time is were the french reaaaaally goofed big time; and it is way too late to make a unit now. Temperature remains a rare animal. Other major goofs are adopting anything not decimal. Longitude and latitude, degrees on a circle, twelve months... It is all messed up. But we have to live with it. At least is not worse than the volume of the urinals of king and queen whatever of England for the imperial and the other gallon, and the size of the thumb for an inch. And a pound that abbreviates lb instead of pd?. What a joke. Miguel

A white towel or a black towel, both equally soaked and under same test conditions in the shade ?