Wikipedia:Reference desk/Archives/Science/2012 July 6

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Science desk
< July 5 << Jun | July | Aug >> July 7 >
Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 6[edit]


Bay Laurel magnolia laurus nobilis virginiana, a flowering angiosperm.

Angiosperms are commonly known as what plants? — Preceding unsigned comment added by (talk) 03:38, 6 July 2012 (UTC)

Flowering. (talk) 03:41, 6 July 2012 (UTC)
Oh, are we playing Jeopardy? ~sniffs disdainfully at the IP who answered first but failed to do so in the form of a question~ What is a flowering plant, Alex? Snow (talk) 05:05, 6 July 2012 (UTC)
I thought Jeopardy clues didn't have question marks?A8875 (talk) 05:27, 6 July 2012 (UTC)
That's true - the full Jeopardy formula would produce something along the lines of "These plants, classified as angiosperms, are better known by this common name." But you can't deny that this seems to be more of a quiz than a refdesk question, since the OP obviously knows the answer. And he even gave us a picture assist as they occasionally do on Jeopardy, I seem to recall. :) Snow (talk) 08:13, 6 July 2012 (UTC)
OP didn't add the picture, added the picture along with a response. I agree OP was probably quizzing us. His reasons for doing so is unfathomable to me. A8875 (talk) 09:00, 6 July 2012 (UTC)
Maybe he just wants to participate. ;) Snow (talk) 10:50, 6 July 2012 (UTC)

I need to know[edit]

I am not quite sure of my religion, nor my beliefs. Only that I have so many questions that I want to ask but yet to have found answers. I just don't understand how some one could believe that out of nothing, pure NOTHING. blankness, nothing. NOTHING! Something called "God" appeared, or apparently always was... I don't get it. So, in my head i picture whiteness. Nothing but pure whiteness. A blank screen. And then there is "God" who apparently has always been in this pure nothingness. And out of all that nothingness, "God" created everything. Put the world through cycles.. Then had Mary and Joesph birth his son, "Jesus". And "Jesus' carried his word thru out the world. the world advanced and this is what has become of it. How do we know that Heaven and hell exist? we would only know if we had died, and no one can die and then come back and tell us that its real... With the way the government hides and lies to us, it's hard for me not to think this is just another scam they have. If so, i believe its a sick joke.. Like I said, I never said I don't have FAITH, I just don't understand.. Every time I ask these questions every one yells at me and says I am not a believer and that because I want to know these things I don't believe in god. I just want to know where God came from, and how we managed this. And if he created human, what is he? Or she? How do we know any of this is real? I just want to know.. and I know I probably won't get much of an answer back. But, it's worth a try. i am just a very factual person, I need facts. I love science and it's getting in the way of having complete and udder FAITH in this mystical creature who has always existed in pure nothingness, that has some sort of power to be able to create the Earths, the Heavens, the Hell's, and so on and so on. Time and space, god is above that? How can we explain that God is above time and space. Doesn't that sound more scary then good? I don't know.. He has this infinite power, that controls everything. He knows everything you think, everything you do, and he takes all your actions upon you at the day of your death to decide whether you go to hell or you come to heaven. What if because I have these questions, and these doubts that I go to hell? I have a question and that makes me wrong? I want facts, and that makes me a sinner? I want to know where this something came from that I am supposed to believe is almighty, and I am sent to hell? That's cruel. I am sorry, but if because I have questions about this, and it condemns me to hell, God sounds more like he is a punisher rather than our savior. — Preceding unsigned comment added by Aantoinette (talkcontribs) 05:25, 6 July 2012 (UTC)

Which is how we know that God does not exist. Whoop whoop pull up Bitching Betty | Averted crashes 05:29, 6 July 2012 (UTC)
A couple thoughts:
1) Both science and religion have the same flaw, in my opinion, that neither can tell us what happened before a certain time (The Creation/Big Bang). They can say that God/the universe always existed, but that's just as bad of a cop-out, to me.
2) I find Eastern religions, with their balance of good and evil gods/forces to be a better explanation than the Abrahamic religion concept of a single, infinitely good, and infinitely powerful God. Clearly, evil happens in the world, and so God either can't prevent it, or doesn't want to, which makes him either not infinitely powerful or not infinitely good. StuRat (talk) 05:34, 6 July 2012 (UTC)
Aantoinette - you say that you do have faith, but "Every time I ask these questions every one yells at me and says I am not a believer and that because I want to know these things I don't believe in god." It sounds like you may be surrounded by some pretty intolerant people. And I wonder what you do have faith in? Keep asking the questions, but not among those with unquestioning minds themselves. HiLo48 (talk) 05:58, 6 July 2012 (UTC)
StuRat, I think you are confused about science. No real scientist will say that the universe has always existed, it began about 13.7 billion years ago. As far as "before" the beginning, the consensus seems to be that asking "What happened before the Big Bang?" has no meaning; it's like asking "What's south of the South Pole?".
Science has its flaws, but comparing to religion is pointless. To paraphrase Tim Minchin, science is formulated based on observations; religion relies upon the denial or absence of observations to preserve faith. They are incompatible systems, and I for one am a fan of the one that invites skepticism and allows anyone to test and verify the results, not one that quashes dissent and forces uniform belief based on nothing but faith.
To the OP, if you're looking for religious guidance, I think you have gone astray by asking at the Science Desk.-RunningOnBrains(talk) 06:09, 6 July 2012 (UTC)
I believe some scientists have speculated about what happened before the Big Bang. There was the oscillating universe theory, then there are more modern cyclic model theories, and a multi-verse theory which proposes that big bangs are going off all over the place, creating their own universes, perhaps each with slightly different string theory parameters. StuRat (talk) 06:43, 6 July 2012 (UTC)
For Stu's claim, it's yes and no. Any serious theory that provides a "before" to the big bang still has to come to grips with a beginning at some point. Except for Hawking's theory, which many physicists agree with, in which time began with the big bang. In this formulation, there was no "before". Hawking then waves his hands (or he would, if he could), and declares that no moment of creation is required, nor anything previous. I don't have the physics expertise to understand and evaluate his idea. Someguy1221 (talk) 07:19, 6 July 2012 (UTC)
Yes, actually some of those theories have seen a resurgence of late, now that computational processing has become so powerful that the list of candidate contour models for dimensional variation at the string-scale has grown to an astronomical size. The idea of co-existent multiverses is an elegant solution to the question of why our universe happens to exist within its set constraints, but it's highly speculative. Now that the standard model is nearing complete validation (or as complete as its likely to get, in any event), it will be interesting to see where research in this area heads, since string theory is such a prominent contender as a unified field theory. Snow (talk) 08:59, 6 July 2012 (UTC)
The problem with Stu's analogy is that he compares a first order assumption with an extrapolated assumption. The universe exists, we know this for a fact as it is simply the name we give to all of the collective phenomena which compose the observable existence around us and - baring certain abstract spiritual, existential, and metaphysical arguments - we make this a basic assumption of all further arguments about its nature, such as whether it has always existed or has a definable age. This is a very different issue from the question of whether God exists, which is not an empirical first-order assumption since we stipulate existence anytime we engage in observing any principle, phenomena, or issue. Snow (talk) 08:41, 6 July 2012 (UTC)
Dear OP: You seem to have absorbed a second-hand folk version of both Christianity and scientific cosmology. My advice to you is to read and absorb what's been said above to understand more about the Big Bang. (The 'nowhere south of the South Pole' explanation makes sense to me and accords with my understanding of what Hawking et al have said.) For the religion questions: break them down into smaller units - 'Is there a God?' 'Who was Jesus?' 'What, if anything, can the historical Jesus (if there was one) tell us about our lives today?' 'Does belief in God and/or Jesus require belief in Heaven and Hell as they have been explained to us by the churches?' 'Does a belief in religious morality necessitate a belief in Heaven and Hell? How about vice versa?' 'What other religious paths are there, and what are their merits and problems?' If you want to know what others have said on these topics, try researching, or asking on the Humanities desk. Heck, I'm happy to discuss this stuff on my talk page. AlexTiefling (talk) 10:31, 6 July 2012 (UTC)
All good advice, though I suspect the OP is probably already well on her path towards an agnostic/atheist perspective if she feels such a strong disconnect with the dogma she is familiar with and what seems intuitive to her, despite the fact she is apparently surrounded by religious fundamentalism in her daily life. She also seems to prioritize the value of the empirical process which, although not necessarily mutually-exclusive to religious faith, often takes root in a certain type of person and fills the basic role of central guiding principle that religion serves in many others. Snow (talk) 10:48, 6 July 2012 (UTC)
Oh, I agree. I'm not suggesting that responsible answers to the proposed questions will lead anyone to adopt or re-confirm a religious faith. Rather, those are the sorts of questions to ask (along with 'says who?') in order to tease out what we understand by religion at all. Asking them in the enquiring and empirical spirit you suggest is a good idea. AlexTiefling (talk) 11:33, 6 July 2012 (UTC)
Yeah, I know, I caught your meaning, and you're right, she'll have to deconstruct things to make sense of them and decide how much, and how quickly, to transition from her current beliefs. I just mean to add by way of addendum that if she's as incredulous about those concepts as she is already, she might go very quickly from the "How does this really add up?" stage to the "Yeah, I'm over it entirely - let's hear another perspective" But who can say for sure? Snow (talk) 13:30, 6 July 2012 (UTC)
Much of this is beyond what science can answer - but at least note that the rule with science is that when you try to penetrate to the very truth of things, things get weird. The Big Bang is a mathematical breakdown in calculations; it's not actually a model for something from nothing. It might be saner to use the logarithm of "time", as we define it, from the Big Bang until today, in which case there is no beginning. And in the Copenhagen interpretation of quantum mechanics, one can argue that there was no "collapse of the state-vector" before conscious observers - that in fact, before the advent of man, the universe was a superposition of countless states, and only when first he looked up to the sky were the positions of the stars determined. That's not even getting into high but perhaps purely hypothetical weirdness of Membrane (M-theory). So if you get the feeling that science has to give you some simple, comprehensible answer about the first origins of things - don't count on it! Wnt (talk) 12:35, 6 July 2012 (UTC)
Well not in our lifetimes anyway. But the OP doesn't seem to me searching for absolute resolution to any question so much as questioning the foundation of explanations that have been given to her in the past. Even when science -- or more broadly empiricism, since we're not talking about formal processes alone here -- fails to give us complete answers or leaves us with more than we had when setting out to a resolve an issue, it can still be a comforting and rewarding process. It's dependable, even though it doesn't give us the answers we expect or want. I suspect that this is what the OP is trying to suggest she gravitates toward - that sense that, even if science/empiricism doesn't give us everything all at once, at least it gives us a framework that we feel we can build from, constructing larger and more complex principles from more basic ones and having it feel consistent, verifiable and honest. It's predictive and explanatory capabilities may not be unlimited, but it's better than taking on faith ideas which you feel are inconsistent with the world as you've observed it to operate. That's really the OP's only other choice in the context she's described. Snow (talk) 13:14, 6 July 2012 (UTC)
To the OP, I have more of a practical recommendation for you than an answer to any of the particular issues you raised. Try finding a copy of Carl Sagan's Cosmos. It's a simply brilliant work which examines many of the concepts you're wrestling with but, more broadly, is simply an excellent primer to the scientific method and how it has slowly evolved to tackle issues of both cosmic and human scale. Sagan had an ability, which I have never seen surpassed in my lifetime, to distill complex ideas down to their elementary points in a way that is exceptionally clear and accessible to almost anyone and yet is also undeniably poetic. You could certainly do a lot worse as a place to start for someone who's trying to understand the big picture and begin to put human experience in perspective with regard to the enormity of the universe. It's a little dated at this point (visually I imagine it will look almost archaic), but it could give you a good leg up in tackling your nagging questions. Trust me, you're gonna thank me.  :) Snow (talk) 13:50, 6 July 2012 (UTC)
And there's also the accompanying book, if you prefer reading over watching. StuRat (talk) 02:19, 7 July 2012 (UTC)

Time doesn't exist in the first place. There only exists a multiverse, which is a timeless entity. Count Iblis (talk) 15:29, 7 July 2012 (UTC)

Ethics is more important than religion. Do you want to believe in a God who would command you to sacrifice your firstborn son to test your faith? My God is neither evil enough to do that nor too stupid to have understand evolution. Figure out what you believe in and then pick a God who lives up to your expectations. μηδείς (talk) 23:46, 7 July 2012 (UTC)

A Universe from Nothing can be an interesting reading here, if you want to speculate about "Why There Is Something Rather than Nothing." OsmanRF34 (talk) 20:18, 8 July 2012 (UTC)

Extreme weather damage[edit]

What is the best way to characterize the two graphs here? I've asked for help at commons:Commons:Graphic Lab/Illustration workshop#Extreme weather damage to combine the two graphs, and that would be great, too, but what is a fair summary of the both of them in words? (talk) 05:59, 6 July 2012 (UTC)

They both indicate increasing damages from storms. However, I'd stick with the raw data, and avoid those lines and curves they added. Especially on that first graph, those lines look rather suspect. First there's the assumption that any change would be linear. Then there's the actual fitting method they used. And I suspect that they intentionally chose a year of low storm damage as the starting point, to make it look worse. The red line, in particular, seems out of place. It shows a 50% increase in earthquakes, tsunamis, and volcanic eruption, but why would any of those be caused by global warming ? I'd leave that off the graph entirely. Also, since they mean to rule out natural cycles, they should show them on the graph, in particular El Nino, and perhaps the sunspot cycle, since that might affect electrical storms. Also beware that monetary damage from storms is affected as much by poor construction decisions (where they build and how they build) and the economy (property values) as it is by the weather. StuRat (talk) 06:22, 6 July 2012 (UTC)
(edit conflict)
If I had to characterize the first chart, it seems to be almost pseudoscientific. What characterizes an "event", exactly? What is a "mass movement"? What is a "storm"? Why are non-meteorological geologic events included in this graph? This is a bunch of nonsense to try to find certainty where there is none. The second graph is begging the question as well; of course storm-related damage is going to increase as the GDP and population increase, in addition to the spreading of population into more disaster-prone areas. It conveniently omits hurricane damage to focus only on thunderstorm damage because 2011 was an extreme year for tornadoes. If you normalize the data for population and wealth changes, the chart would probably look more like this chart of hurricane damage, which shows no significant trend.
These authors are clearly into the climate change debate politically and not scientifically: they are mining for "scientific data" to support their conclusions, disregarding any other data. Dishonest science is dishonest science, no matter what side they're arguing for. Data may overwhelmingly point to a warming planet, but science still can't say anything for certain about its implications for small-scale events like tornadoes, hurricanes, and other storms. I would say that if you want an honest assessment of scientific views on climate change, our Global warming article is actually pretty well-done. -RunningOnBrains(talk) 06:26, 6 July 2012 (UTC)
Agreed. Note that the Huffington Post is a liberal web site, and, as such, they don't provide unbiased news. Neither do conservative media outlets, like Fox News. I'd stick with data provided by scientists who aren't on the payroll of either liberals or conservatives. StuRat (talk) 06:34, 6 July 2012 (UTC)
Both of the graphs claim to be from Munich Re, and in both cases the y-axis is financial damage, over time. I am not asking about the bias of the publisher, only the reinsurer's graphs. (talk) 07:02, 6 July 2012 (UTC)
You asked for how we would characterize the charts...I replied that I would characterize them as pseudoscientific and/or misleading. That's the answer. I can't come up with a "fair summary" of something that appears to be vague at best, nonsense at worst. As far as the second graph: without knowing what they mean by "thunderstorm insured loss" (does this include tornado, wind, hail, lightning, flooding, or some combination?) I can't give a "fair summary", as you say.-RunningOnBrains(talk) 08:12, 6 July 2012 (UTC)
Munich Re has a fiduciary duty to accurately report insured losses, and a legal obligation to provide an honest assessment of how they see the future of their insurance business, otherwise their shareholders could sue them. So I would assume their data is accurate as to their business. If what you care about is their business, then that is fine. That said, the graphs may be misleading about the underlying climate trends because of confounding factors like population growth in vulnerable areas, changes in property values, changes in the number of policies written by Munich Re, and other factors. One is likely to get more useful information about climate by looking at climate / weather patterns directly (e.g. number and intensity of storms over time). Dragons flight (talk) 21:10, 6 July 2012 (UTC)
This is probably a better way to say it than I did. Certainly the charts may have legitimate uses for actuaries and insurance companies, but without knowing more about what data they are plotting the graphs are useless.-RunningOnBrains(talk) 21:44, 6 July 2012 (UTC)
Okay, given all that, and assuming only [1] and [2] are accurate, what is the correct way to characterize their data? Also, what does the ratio between earthquakes and weather events say about the extent to which population shifts are responsible for the characteristics of the data? (talk) 23:24, 6 July 2012 (UTC)
Well, the lines on the first graph simply aren't described in the key, so we can't tell if they are least sum of squares calculations, or what, or even if all the lines are calculated in the same manner, or perhaps just drawn in by hand with no calculations behind them at all. But, if you did take them to be accurate representations of the overall trend, and if you assumed that the 50% increase in earthquake/tsunami/volcanic eruptions was due to the increases in population and property values in dangerous areas, and if you assumed that the same changes also occurred in population and property values in areas affected by climate-related disasters, then you could do some math.
Since 100% is 2/3 of 150%, you could then multiply that 2/3 by, say, the 300% in a climate-related category, and get 200%, meaning that the damage doubled in that 30 year period for reasons other than population growth and property value increases. I'm sure you will assume this is due to climate change, but we really can't tell that from this data alone. StuRat (talk) 02:04, 7 July 2012 (UTC)
What additional data do we need to know to isolate the proportion of the increase due to increasing extreme weather instead of population shifts? Would it be better to plot either or both graphs on a log scale y-axis? (talk) 06:03, 8 July 2012 (UTC)
You want to have actual data on the population growth and changes in real estate values in the areas in question. For example, if you are looking at damages in Dade County, Florida, what has been the population change and real estate value change in Dade County over that same period ? Of the two, real estate value change is the more important, as presumably the population change will be reflected in that. Once you have that, you can adjust the damages, just as I did above by assuming that non-climate changes represented changes in population and real estate values. StuRat (talk) 06:12, 8 July 2012 (UTC)


How is calcium-48 produced for the experiments making superheavy elements? Is it simply separated out of natural calcium? If so, how is it separated? (Cites please, because I'm putting this into an article – ununseptium – which is currently at GAN.) Double sharp (talk) 14:22, 6 July 2012 (UTC)

I can find several references to different methods, but nowhere does it state which (if any) are preferred. Chemical processes seem to be the most-referenced, especially chemical processes involving crown ethers and chemical processes involving sulfonic acid. This book notes that the "liquid thermal diffusion" method may be feasible, but doesn't address calcium-48 directly for this method; it also notes that mass spectrometry (specifically using the Calutron) is less feasible for Ca-48 because it takes far longer than other methods. Single-photon atomic sorting is proposed as a method for sorting Ca-44, but I believe it only works on certain isotopes and would likely not scale to Ca-48. This NASA technical paper might also contain helpful information judging by the title, but it's not available online so you'll have to request a (free) copy. -RunningOnBrains(talk) 22:09, 6 July 2012 (UTC)

Detonator ?[edit]

Hello learned ones ! How do you call the wooden box with a handle Cl Nicholson falls on, triggering the blowing up of the bridge, in the film « Bridge on the river Kwai » ? Some around me tell me it's a detonator, but I thought detonators were crayon shaped and sticking to the dynamite baton (the kind of little thing which explodes in his lap & disembowells the young Arab , close friend of Lawrence, in the film « Lawrence of Arabia »...) . Thanks a lot beforehand for your answers ( & sorry if my cinema references are a bit outdated...But so is the wooden box with a handle, isn'it ?... Arapaima (talk) 16:00, 6 July 2012 (UTC)

The short answer is that those are both detonators, as are the small devices that used to be placed on railways tracks to provide emergency warnings. Anything which causes a detonation is potentially a detonator, although it is common to restrict this to mechanical devices, and call the chemical ones fuses. AlexTiefling (talk) 16:04, 6 July 2012 (UTC)
The stereotypical box with the plunger is not a detonator. A detonator is a device that contains primary explosive wich explodes to initiate the detonation of the main explosive. The box with the plunger is an electrical generator that provides the impulse to the detonator to make it explode. Roger (talk) 17:10, 6 July 2012 (UTC)
So that box is a magneto ? Thanks a lot Alex & Roger . Arapaima (talk) 17:44, 6 July 2012 (UTC)
I think the more modern ones contain a battery, and the plunger closes a contact, connecting the battery to the explosives by wire. StuRat (talk) 18:21, 6 July 2012 (UTC)
Related to a detonator, a blasting cap is a small explosive device that triggers a larger one. That might be what you saw in Lawrence of Arabia. StuRat (talk) 18:21, 6 July 2012 (UTC)
Yes, to differentiate it from others its better known as a 'plunger detonator.' It's mode of operation is that the spring hold the plunger up against the 'shorting link' which guards against induced currents from nearby electric storms and such like from initiating an unscheduled detonation. Quick depression of the plunger, spins a magneto which charges a capacitor and at the bottom of the stroke, a pair of contacts discharges the stored energy down the wires to the explosive detonator charges. As the magneto has mass, a far mount of force is required to be applied perpendicular to the base, in order to spin it up from stationary. Therefore, either Colonel Nicholson intentionally fell onto the 'plunger detonator' squarely and thus avoiding it tipping over or Alec Guinness stumbled onto a cheaply made film prop or possibly both. Other types incorporate a crank handle to turn the magneto (like the old telephones one see's in old movies) to charge the capacitor and separate switches to set the circuit and a button to fire. All done without the need for batteries. They don't tend to have enough energy to set off more than one detonator on a long cable run.--Aspro (talk) 18:25, 6 July 2012 (UTC)
Apropos your first two sentences Aspro, see here for the usual disambiguation. DriveByWire (talk) 21:38, 6 July 2012 (UTC)
Thanks, You have confirmed my suspicions that I knew there was no point in reading things like Eats, Shoots & Leaves when I have volunteers like you to correct my punctuation. Tell me, is there one or two t's in pedantic? [3] :¬) --Aspro (talk) 22:04, 6 July 2012 (UTC)
StuRat is, as is often the case, partly right. The modern equivalent of a plunger detonator are indeed battery powered. The one I have used ran off 4 1.5V "D" cells, and contained an electronic invertor to charge up a capacitor, just as the old plunger-generator types did. So there is no plunger, as there is no generator to turn. To set of the explosives, you insert and turn a key (which was spring loaded to the off/safe position) to activate the invertor, and then push a button to detonate. This gives equivalent safety against accidental detonation (detonation circuit is safe until button pushed, system requires two hands in a deliberate action). Actually, its a bit more safe, as only the licenced powder monkey has the key. Keit124.182.149.215 (talk) 02:07, 7 July 2012 (UTC)
There's nothing outdated about Lawrence of Arabia. David Lean considered it his finest achievement, and millions of movie-lovers have agreed with him. Montgomery Clift, Anthony Perkins, Marlon Brando and Dirk Bogarde were all seriously considered for the title role. Bogarde fought to secure the role, and regarded the studio’s rejection of him the greatest disappointment of his career. It was offered to Albert Finney and Richard Burton, who both declined it. It finally went to a virtual unknown, Peter O'Toole. If you’re below a certain age, these names might not mean a great deal to you, but this was a very big deal (boy, that really dates me). It’s probably time for a remake now. Not to prejudge anything, but it will not be as good as Lean’s film. -- ♬ Jack of Oz[your turn] 04:12, 7 July 2012 (UTC)
That's a bit like saying "Nothing personal, but you're an (insert unrelenting stream of insults here)." :-) StuRat (talk) 04:37, 7 July 2012 (UTC)
Thank you for the interesting aside about an epic film classic. LoR is a 50 year old film about events 95 years ago, reflecting a different political and technical world than encountered today. Thus it is dated if not outdated. Here is an antique blasting machine. DriveByWire (talk) 13:28, 7 July 2012 (UTC)
Here is another opinion on the name of the device: "blasting machine". It's got a picture of Wile E Coyote so it must be the real thing. Googling suggests that "blasting machine" is still a current term in the industry, and is used for the modern solid-state types as well as the iconic generator type. See this commercial website for example. --Heron (talk) 10:07, 7 July 2012 (UTC)
Thanks awfully to all ! Why dont you write an article "Blasting machine" in WP en, I'll be glad to translate it into french. Jack, I'm not too young to know the actors you mentionned, I even saw "L. of Araby" when it came out, and again several times (on a wide screen) in the past decades. And I think it has not a chance to be done again, thanks godness...Glad my question arose your interest. See you, Arapaima (talk) 15:51, 7 July 2012 (UTC)
I can't resist creating such a cool article, so it now exists. I'm putting this on record in case I get a dawn visit from the fuzz. Unfortunately I live in a country where even electronic cigarettes are viewed with suspicion and fear. --Heron (talk) 18:31, 9 July 2012 (UTC)
Heron's article Blasting machine now needs expanding. Are the any Inkscape artists out there that can generate some diagrams?--Aspro (talk) 22:25, 9 July 2012 (UTC)

Why do consumer electronics use DC?[edit]

Couldn't they just use AC like motors, toasters, hair dryers and lamps? OsmanRF34 (talk) 16:43, 6 July 2012 (UTC)

Because the electronics you are thinking of use batteries. Batteries are DC. (talk) 17:27, 6 July 2012 (UTC)
That isn't the only reason. Most sophisticated electronic circuits require DC in order to work. Looie496 (talk) 17:57, 6 July 2012 (UTC)
Circuits use DC from the time that consumer electronics were not portable. (talk) 18:17, 6 July 2012 (UTC)
Also, DC is less dangerous, allowing higher amperages without risk of electric shock. -RunningOnBrains(talk) 18:01, 6 July 2012 (UTC)
I don't believe DC is less dangerous for the same voltage + ampere. But AC is held to be more likely to stop your heart and DC is held to give a stronger "can't let go" factor. Under the wrong circumstances, either will ruin your whole day. (talk) 18:17, 6 July 2012 (UTC)
The real reason: circuits use electricity as a signal. Using AC, which per definition is alternating, it'st much more difficult, when not impossible. The examples that you cite above use electricity to move something. (talk) 18:17, 6 July 2012 (UTC)
Semiconductor electronics intrinsically only work with "one-way" electron flow, so the "reverse" half of the AC cycle will either be wasted or destroy them. And some devices need a constant source (for example, to maintain RAM storage), so the pulsing nature of AC causes problems each time it cycles (60 Hz is too fast for you to notice your lights flickering but computers do a lot of work in each 1/60th of a second). DMacks (talk) 18:49, 6 July 2012 (UTC)
I bet there's some really wacky way to code digital bits and logic gates and so forth using purely AC current and lots of inductors... but I have no idea what it is! ;) Wnt (talk) 21:20, 6 July 2012 (UTC)
It is not wacky, merely inefficient, to store data in non-volatile RAM during an off period while a digital circuit waits for the next supply voltage pulse. DriveByWire (talk) 21:44, 6 July 2012 (UTC)
I think Wnt was referring to Magnetic-core_memory.A8875 (talk) 21:52, 6 July 2012 (UTC)
Wnt, what you are thinking of is magnetic amplifiers. It is quite readily possible to make both amplifiers and memory devices, and combinatorial logic circuits with magnetic amplifiers. See Although the WP article says there is an upper frequency limit of 200 kHz, that was the technology of the day. There is in fact no theoretical upper limit, and with modern ferrites, it could go at least into the MHz region. Magnetic amplifiers use an AC power suource instead of DC, and were very reliable, but were driven out of the market by the considerably cheaper bipolar transistor, which uses DC power. Keit120.145.18.164 (talk) 04:53, 7 July 2012 (UTC)
The reason why analog electronics uses DC power and not AC power is partly historical and partly economic. Conventional electronics is based on transconductance or transresistance control - the input signal controls electrical conductance or resistance of the output circuit of the fundamental component of electronics - the amplifier. If the power source is DC, transconductance and transresistance amplifiers inherently reproduce the input signal (at the larger level) at the output. You can also build an amplifier using transcapacitance or transinductance - such things are called parametric amplifiers. Parametric amplifiers use an AC supply as their power source, but the AC source must be high frequency, not the standard 50 Hz or 60 Hz power frequency. Providing the high frequency AC power is a lot more expensive than providing DC. Parametric amplifiers have been used in specail applications requiring very low noise, and very high frequencies (up into and past the visible light region) where transistors won't work (using gunn sources and lasers as the power source), but for everything else, conventional DC powered transistor circuitry is a heck of a lot cheaper. That's the economic reason. It's much simple to undertastnd the operation of DC powered tube circuity (and transistor circuitry) than it is to understand parametric circuitry. Both are well within the capability of modern electronic engineers (I have designed and built parametric amplifiers myself, which proves it!), but in the early days of radio, it was of course the simpler techniques that got done first. That's the historical reason - the early radios set the pattern of DC powered circuits. Incidentally, the Wikipedea article on parameteric amplifiers is pretty poor - its written at an academic level so ordinary mortals won't get much from it, and it contains some serious mistakes - eg stating that a transresistance element is required - not right, and it seems to be implied that the power source must be harmonically related to the output - true only for certain classes of parameteric amplifiers. Keit120.145.195.13 (talk) 10:41, 7 July 2012 (UTC)

For the same reason a mill powered by a water wheel needs a flowing stream and not a sloshing lake. μηδείς (talk) 23:42, 7 July 2012 (UTC)

Quite apart from μηδείς not considering wave power, he's used an inappropriate analogy. The basis of electronics is amplification - creating a larger amplitude replica of the input signal. A water wheel is NOT an amplifier, it ia a hydro-mechanical transformer, in which its output power is less than the power going in. The OP essentially asked "can AC be used as a power source for electronic circuits instead of DC?". And the answer is "Yes it can, but in nearly all applications it is not cost effective, and the AC required is not the convenient 50/60Hz used in the lectrical power industry". In special applications (low noise amplification of faint signals from outer space being a fairly well known example) AC (with parametric amplifiers) IS used as the power source. Keit120.145.130.198 (talk) 03:05, 8 July 2012 (UTC)
The lead about the mag amps above is certainly interesting and welcome. Our article says that they are like, but different from, transformers, and I don't pretend to understand the devices as of yet. But apparently it is possible nowadays to put a "transformer on a chip" [4]. Does this mean that a mag amp based digital logic chip could be made, which at least would be much more compact and powerful than the old UNIVAC Solid State (though I should say, I haven't confirmed that used AC for logic operations anyway). Wnt (talk) 23:26, 8 July 2012 (UTC)
Those old Univacs used normal DC-powered logic. Only main storage was magnetic, as with all computers at that time, using techniques somewhat similar to audio tape recording, with drum surfaces instead of tape (tape was used as well). As boffins can make just about anything on a chip these days, and therefore a transformer, that would mean they can make a magnetic amplifier, assuming integrating insulated conductors and ferromagnetic elements can be done. A ferromagnetic core is not fundamental to a transformer, but it is essential to magnetic amplification and storage. But I can't think why they would want to. Transistors are always going to be smaller, and as chip space is expensive, that means (DC-powered) transistors are going to remain much cheaper. Keit60.230.203.147 (talk) 01:21, 9 July 2012 (UTC)
Ruggedness seems the only remaining advantage of magnetic amplification and storage over vastly denser transistor ICs. I am thinking of EMP resistance (not usually considered in consumer electronics). DriveByWire (talk) 03:00, 9 July 2012 (UTC)
Yes, that's true. Magnetic amplifiers inherently have very good immunity to EMP and electrostatic discharge, unlike MOS transistors, and they also are a lot more immune to high operating temperatures and temperature cycling. And with reasonable care in construction, a little better in regard to mechanical shock and vibration as well. Keit124.178.32.100 (talk) 09:52, 9 July 2012 (UTC)

Perhaps a related question should be covered, why use AC at all? Mainly because it made moving electricity long distances practical/feasible/easier/cheaper than using DC transmission lines, using the technology then available (transformers) when electricity was just becoming a more widely used power source, such as in Thomas Edisons day, the mid-late 1800's. (Edison was a vocal advocate of DC power distribution by the way.) This is no longer true as long distance High-voltage direct current distribution is now often used, when appropriate, such as transferring power long distances where DC has inherent advantages (less loss) over AC, and is now more economical then pure AC transmission. (In 1980 longest cost-effective distance for DC electricity was determined to be 7,000 km (4,300 mi). For AC it was 4,000 km (2,500 mi), "... limits of very long distance transmission ... " CIGRE)

As Looie496 pointed out "Most sophisticated electronic circuits require DC in order to work", and DMacks "Semiconductor electronics intrinsically only work with "one-way" electron flow". To expand on that, it seems to me that the physics of 'active' semiconductor devices (like transistors vs. 'passive' resistors) usually require direct current (rather than alternating) to work. (Keit60.230.203.147s' Parametric amplifiers being an exception.) A basic transistor cannot work in AC to directly amplify an alternating current signal). You can (I think, not 100% certain) use 2 'complementary' (NPN & PNP pair) transistors to seperately amplify each half-cycle of an alternating signal (push-pull amplifier).

The OP OsmanRF34 (talk · contribs) asks: "Couldn't they just use AC like motors, toasters, hair dryers and lamps?" These 'passive' devices, for the most part don't care whether the electricity entering them is AC or DC, heaters epecially. It may make a difference to their design, but a wire (heater, incandescent lamp) will heat up from AC or DC current. Synchronous motors used in many AC powered devices do however require AC, but could likely be replaced by a DC motor in most, if not all applications.
N.b I am an electronic technician, though mainly in Radio, by 'trade', so Mains electricity is not my most qualified area to reply to. ;-) 220 of Borg 20:36, 9 July 2012 (UTC)

You may, however, be a very good electronics technician, 220 of Borg, because you have distilled into one sentence what the rest of us (including me) have woffled around: The devices the OP cited are passive devices (devices that only dissipate or transfer power, and electronics is based on active devices (devices that transfer power under signal control) - it being easier to design/engineer active devices if they are powered by DC. Keit121.221.86.127 (talk) 04:18, 10 July 2012 (UTC)
Face-blush.svg (blush) I wish! I spent time I should have been sleeping chasing up the refs, WP links, and editing my reply. Glad you liked it. Funnily enough I am now working in dimmer, battery charger & high current power supply manufacture & repair. 'Keit' I suggest you get assimilated into the Wiki-collective. It makes editing much easier! And I wouldn't have to reply here as you would have a talk page. - 220 of Borg 11:28, 10 July 2012 (UTC)