Naked Science Forum
General Science => General Science => Topic started by: Joe L. Ogan on 11/01/2011 23:52:18
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What is electricity? When I was a young boy, I remember the teacher asking the same question from one of the students. The student said, "I am sorry, teacher, I did know that but I have forgotten." The teacher said, "My God, man, no one else has ever been able to tell what electricity really is. You knew and now you have forgotten." My question is, "Have any of you learned scientists ever come up with a better answer?" Thanks for comments. Joe L. Ogan
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Electricity is the movement of electrons down an energy gradient, usually using a medium that supports a delocalized electron cloud such as metals, or graphite.
(It is noted that many organisms support an electronic gradient of ions, and perhaps that is one of the aspects of batteries).
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Electricity causes a movement of electrons but I do not believe one can define something by what it does. If one should accept that the premise of defining something by what it does, it might be said that electricity is heat because it causes the electric stove to become hot. Thanks for comments. Joe L. Ogan
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Electricity causes a movement of electrons but I do not believe one can define something by what it does. If one should accept that the premise of defining something by what it does, it might be said that electricity is heat because it causes the electric stove to become hot. Thanks for comments. Joe L. Ogan
If you want to start on semantics I would say that Clifford's explanation is closer to 'how' electricity -is-(ie. happens) not 'what' it -is- (that you've taken to mean -results in- for some reason).
Are you asking a scientific or philosophical question? Define what aspect of Electricity you are having a problem with and we can have a go at answering it - otherwise it's just so much shifting sand.
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Hi, peppercorn. There are so many definitions of electricity that I find it difficult to get a clear-cut definition. There is nothing philosophical about the question, "What is Electricity?" I am not trying to put anyone on the spot. I doubt that anyone can give a clear definition that everyone will agree is right. I have read most of the definitions but they do not promote clarification. Most of the definitions concentrate on what Electricity does. Thanks for comments. Joe L. Ogan
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Most of the definitions concentrate on what Electricity does.
Every single science definition is made on the basis of what something does, because at some level, you make a fundamental assumption of a model based on what it does and build up from there. "What is it?" isn't really a proper question in physics.
I've posted this before, but it's applicable here:
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Have you been appointed to determine whether a question is proper or not before I ask it? Thanks for comments. Joe L. Ogan
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I doubt that anyone can give a clear definition that everyone will agree is right. I have read most of the definitions but they do not promote clarification. Most of the definitions concentrate on what Electricity does.
It seems to me that you are predisposed to expect there not to be a 'complete' definition for this question, but read on...
Every single science definition is made on the basis of what something does, because at some level, you make a fundamental assumption of a model based on what it does and build up from there. "What is it?" isn't really a proper question in physics.
Have you been appointed to determine whether a question is proper or not before I ask it?
I think JP is saying, not that he personally is the overseer of a question's (scientific) validity, but that science is, by it's definition, interested in empiricism. Science should not be interested (at least in it's methodology) in some deep-seated 'truth' - it should look at the world as a serious of ever-more-defined models, that agree to a ever-greater extent with observed reality.
Also, every question like this one needs some context, don't you agree?
For instance, in one context the answer to what is electricity is: Current flow. In another it is electron drift. In yet another it is static charge.
We understand the fundamentals of how electric charge moves, so I think it's up to you as the questioner to be more specific.
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Well, I do not know how to be more specific than the question: "What is electricity?"
I did not know the answer. I still do not know the answer to the question. I rather feel that one does not have to answer a question if they do not want to answer. I do not feel that one has the right to be obnoxious about a question just because they do not know the answer. Thanks for comments. Joe L. Ogan
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What is Electricity, By William J. Beaty is an article in Google that has been most helpful in showing me why I am puzzled by Electricity. For those of you who have the same puzzle as I, please research this article and I believe it will help you to understand why it is such a puzzle. Thanks for comments. Joe L. Ogan
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Joe,
JP was trying to be no more obnoxious than usual [;D]
I don't believe he is saying that you have not asked a proper question, as in, for example,
"What's wrong with you! Can't you ask a proper question?"
It's more likely he means that the question is unbounded, so there can be no definitive answer.
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Hi, Geezer. Well, there appears to be a tendency for people in the forum to jump on someone who has asked a question. Now, I am not tender but I see no reason for people to be obnoxious. I believe that we all should encourge people to be a little more polite. If you catch me being impolite, please let me know. I shall do my best to refrain from such action. I know the question about electricity raises some anxiety on the part of some people. That is normal. But, if someone does not kmow the answer to a question, they simply do not have to answer. Beaty lays it on the line about electricity. Many of the things in text books are wrong. This is not surprising to me. I used to go through my text books in college when I was working on my Masters Degree, and point out the things that were wrong. Thanks for comments. Joe L. Ogan
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I've posted this before, but it's applicable here:
I love this series of talks by Richard Feynman--and it's interesting that you posted this in response to Joe's excellent question. The video really illustrates the problem we have in this thread. Feynman's feathers are visibly ruffled when asked a simple question about a certain physical phenomenon (magnetism). You can really feel that he'd LIKE to answer the question with the same kind of fantastically clear metaphors that he uses when answering other physics questions. (see his other YouTube videos) His hot response must have come from a frustration that he just couldn't answer that seemingly simple question in the same way.
I guess my point is that all we lay people need is a pleasant response like: "We don't understand it well enough to put it into simple terms," from time to time.
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What is electricity?
It is a good question Joe, but awfully hard to answer.
Maybe we should start with asking what a 'force' is?
Electricity is one of the four fundamental forces that we see in this universe. We call it electromagnetism, then we have two forces more that we think us being able to put into a understandable pattern, the Weak and Strong Interaction. The last one, the fourth, we call 'Gravity', but according to General Relativity that's more of a property than a regular 'force', although Quantum mechanics seek to find ways to express it as interactions too, whether by 'gravitons' or by the Higgs mechanism (Higgs particles/bosons).
What we call the 'electromagnetic force' is a unification of the magnetic and electrical forces that, until Maxwell, was considered to be two different forces. Although magnets still present somewhat of a mystery to me I'm not sure all agree :) It depends on your outlook and definitions.
"Electromagnetism is the interaction of particles with an electrical charge. Charged particles at rest interact through electrostatic forces, while in motion they interact through both electrical and magnetic forces."
Did that tell us what it is? Maybe, in a way it did. But then again, what is 'particles'? And 'charge'? What is 'charge'?
What we do Joe is reverse engineering Nature. The more we learn and the more we 'guess' in a educated way, following the 'principles' we think us see, the more we get to know. Now and then, rather seldom, someone like Einstein comes along and turns all upon its head, 'guessing' in a totally different way. Then we, if we find his guesses having a good certification in those experiments we can think up, find new ways to see the relations between what we observe and theory.
We can backtrack electricity a long way but in the end it becomes a question of transfer of energy. And 'energy' is such a slippery subject :)Where does it come from, how can we say that it 'transform' in interactions, and where is its endstate in a entropic universe. Heat is not the answer although entropy discuss that a lot, or maybe it is? But then heat somehow will be the ultimate 'useless' 'energy' that can exist, which seems rater preposterous, don't you agree?
So I prefer to look at 'energy' as a concept, describing transformations and the work we get from it. But I do not know where its end state is, 'work done' as it also is called. 'Work done' is a very diffuse description to me, but as a concept very useful, like 'potential energy' :)
But I know what you mean and I've asked the exact same question myself, more or less. JP wasn't trying to put you 'out on a limb' there, he wanted just to show that it was a question that becomes more of a philosophical one than a question of what we can 'reverse engineer' explaining. A lot of the most important questions are just like that. What is 'death'? And what the he* make us 'exist'? I would like the answers to those, and I guess that so would you :)
They are so hard to find the answers too, but we all try.
And yes, they are all important. Einstein wouldn't have gotten his ideas if he didn't use his imagination and asked questions that to their nature was just 'philosophic', like what he would see in a mirror if he was traveling with it at the 'speed of light'. But I promise you Joe, I've never seen JP being deliberately rude to anyone, and I don't think he meant you to feel that way either, sometimes we all may come across as rude, it happened to me too.
It's a very good question, but the answer will need a Einstein more I think :)
Or two ~,
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I'm not trying to ruffle any feathers, but as it strikes me right now (I might see it differently in the morning)...
It seems to me that the word "electricity" is actually rather poorly-defined but is widely used by laymen (and casually by engineers and physicists who should know better) as a catch-all for various more specific electrical phenomena. As such, trying to define "electricity" too precisely will be a bit of a futile and pointless exercise.
(I see this as being a bit like trying to define "atmosphere" when you refer to the atmosphere of a party or political rally. You might try to describe it in social terms like friendly/aggressive/ tense/easy/ happy/panicked ... but you can't really define the word "atmosphere" as it's somewhat amorphous. I guess I'm arguing that there's a problem with the language, rather than with the underlying physics or concepts. [::)] )
Instead, it's much easier and more helpful for understanding, to follow the concept of electrical potential (or voltage) and electric current (flow of charge). These are much more specific phenomena and therefore far easier to define and explain.
So:
1) electrical potential, or voltage
Most of the time, most things have a neutral overall charge - that is, they contain the same number of negatively charged particles (electrons) as they do positively charged ones (protons in the atomic core). This neutral overall charge also implies no overall electrical potential or voltage.
If for some reason there is an imbalence of positive and negative charges, making an overall net charge then that 'thing' will have an associated electrical potential (also known as voltage). If the object has an excess of negative charge (excess electrons) then it will exhibit a negative electric potential (negative voltage). If it has excess positive charges (a deficit of electrons) then it will exhibit a positive voltage.
(Mathematically, on an insulated item Q=CV, or V=Q/C but let's not worry too much about that for now. Suffice to say that a 'big' excess or deficit of charge corresponds to a 'big' voltage, and 'small' charge imbalence is equivalent to a small voltage.)
This imbalence of charges can be created by rubbing things (like balloons on shirts - so-called static electricity, also by ice/rain drops circulating in thunderclouds), by chemical means (like batteries), and by magnetic means (as in most electricity generators, bicycle dynamos etc). There are some others, but they're the main ones.
2) electric current
Given half a chance, charge (usually negatively-charged electrons) will 'flow' from one thing to another so as to (try to) equalise the overall charge-imbalence between the two items (strictly, to bring them to the same electrical potential).
In the case of "static electricity" where there is no continuing, ongoing source of charge imbalence, you get a brief 'discharge' (brief spark) as the charge (electrons) flows to balence the charge.
In the case of electricity from a battery or from the mains where the battery or power-company transformer is continually 'pumping' (or trying to pump) charge around then if you join the two wires you'll get a continuous, sustained flow of charge (which is referred to as a current). A current of "1 amp" is equal to the flow of 6.24 million million million electrons per second.
So... the "electricity" in your house wiring is merely a man-made non-equilibrium balence of charges in the wires. If you have an appliance drawing power from the socket on the wall then as well as that imbalence of charge, you also have an overall flow of charge (current) from one wire, through the appliance, and back down the other wire.
The "power station" doesn't so much "make electricity" as to create an imbalence of charge (an excess of electrons in one wire and a deficit in the other) with the ability to sustain that imbalence even when lots of customers start connecting appliances which 'leak' or 'bleed' the electrons from the wire with the excess to the one with the deficit. The generator at the power station is a kind of "electron-pump", typically driven by the mechanical motion of turbines of some sort.
Note, in reality mains electricity is AC, meaning the wires with the positive/negative charge imbalence swap sides 50 (UK/Europe) or 60 (USA) times per second. Also because of the AC, and all the transformers the electrons which go through your appliances won't physically go to the power station (they probably won't even leave your driveway) - but they get pushed back and forth in the cable by the 'pressure' of the other electrons further upstream in the cable.
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I like it, it's a practical definition of what it is, fitting the way it behaves. As for the perfect definitions of what 'it is' transferring and how 'it' transfer becoming 'used energy' from its former state of 'usable energy', is more diffuse to me though.
Take a solar cell, energized by the sunlight (waves/photons)."As each photon strikes a silicon atom, it ionizes the atom by transferring its energy to an outer electron, allowing it to break free of the atom." so here we are talking radiative energy, transferring. If it instead had been the atom containing those electrons colliding in some manner the definition would be a 'kinetic energy'. "The energy of the photon is converted into electron movement energy called electric current". (We are also talking 'black body radiation', as well as the 'photoelectric effect' here, that the the solar cells electrons need to 'fit' the energy level of the photons hitting it in order to be released, also called ionization.) And so, on that small plane, it all becomes 'energy' transferring, one way or another to me.
If we look at the 'AC' current you discussed this description fill some info in too I think.
"Do generators make electricity? To answer this question, consider the household light bulb. Inside a lamp cord the charges (the electrons) sit in one place and wiggle back and forth. That's AC or alternating current. At the same time, the waves of electromagnetic field move rapidly forward. This wave-energy does not wiggle, instead it races along the wires as it flows from the distant generators and into the light bulb. OK, now ask yourself this: when "electricity" is flowing, is it called an Electric Current? Yes? If so, then electricity is charge. And therefore we must say that the "electricity" sits inside the wires and vibrates back and forth. Generators do not create it, and it does not flow forward. Next, ask yourself if electricity is a form of energy. If it's energy, then electricity is made of electromagnetic fields, and it doesn't wiggle back and forth within the wires. Generators do create it, and it races along the wires at high speed. But electricity cannot do both! Which one is really "the electricity?" Is it the wiggling electrons, or is it the high-speed EM field energy? The experts cannot agree on a single definition. The reference books give conflicting answers, so there *is* no answer."
From What Is "Electricity"? by William J. Beaty. (http://amasci.com/miscon/whatis.html) He's thought about it too it seems (with lots of nice links:)
Weird stuff it is (Yoda).
Ah, Joe. Seems we have the same taste :)
Missed that you already mentioned him until linking.
I agree, he's one of the best I've read on that subject.
I like his "SPEED OF "ELECTRICITY"" too, and the comments afterwards.
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It is my understanding that the speed of an electrical current is very slow, about a millimeter per second. Thanks for comments. Joe L. Ogan
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Joe,
JP was trying to be no more obnoxious than usual [;D]
I don't believe he is saying that you have not asked a proper question, as in, for example,
"What's wrong with you! Can't you ask a proper question?"
It's more likely he means that the question is unbounded, so there can be no definitive answer.
Oops. Somehow I missed this thread, but someone pointed me to it recently. Geezer is right. I didn't mean offense or to judge the quality of the question. My apologies if it came across that way.
I meant "proper" as in it's a question without a proper answer in physics. Physics doesn't answer what something "is," it only answers what it "does." There have been many models of electricity, each one building on the last to provide more and more accurate results in certain cases, but none of them is 100% accurate or answers the question of what it actually is!
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Yeah, current is defined as rate of flow for the charge/second passing some point, and, by blind luck I have this thoughtprovoking almost current definition of 'charge', somewhere?:)
Let me see if I can find it. Una momento.
===Quote=
Maybe a mammalian analogy would be more enlightening. Think of a conductor as a long field of gopher holes. Every hole is an atom with it's own set of gophers. There is exactly enough room in each gopher hole for 29 gophers (copper gopher holes). And every gopher hole needs 29 gophers to keep itself maintained.
Along comes farmer Battery and he shoots a gopher on one end of the field and releases one gopher on the other end of the field. The gophers in the hole where one was shot, now need an extra gopher. However the new gopher is WAY on the other end of the field. It's much easier to steal a gopher from a nearby hole. So the gophers charge (Yup, the mystical charge) over to the other hole (atom), and steal a gopher (electron). Now that gopher hole needs a new gopher and does the same thing to another hole that's closer to the new gopher.
Rinse and repeat until you get greasy grimy...no wait wrong analogy..Until you reach the far end of the field, and the new gopher gets pulled into the nearest hole that's missing a gopher.
In the end, the new electrons (gophers) don't actually move very far, since there is always a nearby atom needing a negative charge. For an electron to actually move all the way down the field, it'd take a whole lot of gopher killing.
If you want to get really confused about it. Try figuring out the actual electron flow involved in receiving an FM radio signal.
= End of Quote.
By Corvidae.
So charge is better expressed as the gophers?
Or was those the current?