Nsgarch - electric current is a flow of charge and not a flow of electrons. Electrons move very slow - at about 0.1mm/s (drift velocity). I'm afraid that's incorrect. Current flow is indeed a flow of electrons. Electrons ARE the charge carriers, which is why we call this field "electronics" instead of "protonics." The measure of current is ultimately the measure of how many electrons pass a given point in a given amount of time. If you have 6.241 times 10 to the 18th electrons passing a given point in one second, you have one Ampere of current flowing. |
???? I missed it before but that makes absolutely no sense. You can't separate the positive and negative alternations of a signal with a cable any more than you can have a magnet with one pole. He's not talking about the positive and negative alterations of a signal. He's talking about the shield. Specifically, a shield covering a pair of conductors. With such a cable, you can either connect the shield to one end or both ends. If it's connected to both ends, then the shield carries some of the signal current. If you connect it at one end, it's not, however it still provides shielding. It's sometimes referred to as a "telescoping shield." |
What if my pre amp (or TT or phono pre) has no ground pin on the power cord, just the power amp? Consider yourself lucky. Provided of course that the chassis meet Class II specs and don't actually require the safety ground. The safety ground is the biggest source of ground loop and other noise. What orientation now for the shielded IC's? Same as you would otherwise. The safety ground isn't a ground in the traditional sense. It's just connected to neutral back and the service panel and serves as a path for fault currents should there be a failure in the AC mains in the equipment which might otherwise cause the chassis to go hot and create a shock hazard. It doesn't serve any purpose with regard to component grounding. |
Radio signals are in fact induced in in the cable (since shield most likely does nothing to stop it) but because of skin effect they travel on the outside of the cable - shield (field inside cancels). Shielding basically works by two means; reflection loss and absorption loss. Reflection loss is due to the mismatch in the impedance of the shield and the interfering wave impedance. The interfering wave essentially bounces off the shield. Absorption loss is due to eddy currents induced in the shield. Reflection loss is the primary mechanism when the interfering wave is largely E-field (electric field). Absorption loss is the primary mechanism when the interfering wave is largely H-field (magnetic field). |
Almarg Agreed? Works for me. |
I ran across this white paper about a year ago. It may be of interest to you EEs and such. Smoke and mirrors. "We have presented a new distortion model that accurately predicts the audible behavior of the various metals in common use for audio applications." Pretty neat trick given that to date no one has established actual audible differences among cables save for the well known effects of resistance, inductance and capacitance when they're severe enough to cause differences within known thresholds of hearing. |
Herman UH, yes you did. That has been the crux of the disagreement. Please go back and read through the thread and you will find this exchange.
Me.......Because the electrons do not flow in a power distribution system.
You.......Yes, they do. There would be no power distributed if they did not.
Me........They do not flow along the wire like water flows in a hose.
You.......They do indeed. That is NOT saying that an electron at the power plant arrives at my computer monitor. You seem to be laboring under the notion that "flow" can only be in one direction. But there is flow regardless of direction or whether or not that direction alternately changes. If there is no "flow" of electrons, there is no current. No current, no power. Simple as that. |
Herman I never said that to simply Q, I pointed out an error in his statement about current not being the flow of charges. I never said that. |
Herman I took that to mean you disagreed that current was the flow of charges since I don't see any other way to read that statement. I don't see how you could have taken it that way. The original poster claimed that current was the flow of charge, not electrons. I said that was incorrect, that current was indeed the flow of electrons and reminded him that electrons were the charge carriers. In other words, in the context here, electrons and charge were one and the same. If that is not what you meant then I apologize. No problem. By the way, what happened to the rest of your post? When I read it the fist time, I recall your saying something about positive charge carriers in materials other than metals. |
Kijanki Once again - Electric current is a flow of charge ALONE. At 1kHz electrons are practically standing still (vibrating +/-0.0001mm) NEVER MOVING ALONG THE CABLE while charge is reaching destination with almost speed of light (0.6-0.7).
Electrons might be carriers and you can calculate numbers from amperage but they don't "Flow" - charge does. Once again, and with all due respect, you don't know what you're talking about. In a piece of wire, it is the electrons that are the charge carriers. Therefore you cannot have a flow of current without a flow of electrons. The two cannot be separated. With no current flowing, yes, the electrons are just banging around randomly due to the thermal energy in the wire (the lattice vibrates, knocking the electrons about). And at any given point, the number of electrons crossing that point are effectively the same in one direction as the other. Now, if you apply a potential difference to one end of the cable, and assuming there is a load at the other end and it's not just an open circuit, while the electrons will still be banging about, they take on a net drift in the direction determined by the polarity of the potential at the other end and you now have a flow of current as there are now more electrons crossing that point in one direction than are crossing in the other direction. And while the net drift is typically very slow (on the order of centimeters per second), that's simply a function of how much current is flowing and the number of electrons available to participate in conduction. Keeping all else equal, increase the potential and you increase the current and subsequently the drift velocity. Similarly, if you increase the number of electrons available to participate in conduction, you decrease the drift velocity. What propagates at nearly the speed of light is the transverse electromagnetic WAVE that's established once the potential difference initiates current flow. And this I think is the crux of your misunderstanding. You say "..while charge is reaching the destination at almost the speed of light..." This is incorrect. The charge is already at the destination. Again, it's the electrons that are the charge carriers. There are electrons throughout the entire current loop. It's just that those electrons at the end don't start to flow until the electromagnetic wave reaches the end. |
Herman Mr Simple, I decided the stuff in my last post about positive charges really didn't relate to your response so I deleted it. Ah. I didn't know users could edit or delete their posts. Or are you a moderator?
I see what you mean but by defintion current is not the flow of electrons, it is the flow of charge. Since we're talking about cables then electrons are indeed moving about but you don't have to have moving electrons to have electric current since it is sometimes positive charges.
True enough. But since this thread is about cables and posted in the cable forum, I didn't think it terribly germane or productive to discuss electric current outside the context of cables. Since the flow of charged electrons is relatively easy to envision it is used a lot, an analogy to water is often used even though it breaks down if you try to apply to all electrical phenomna. Yes. But the issue under discussion is current flow. And the water analogy is perfectly adequate in this context. However, I do know enough to understand that electron flow can't explain everything happening in electronics. For example? |
Herman Mr. Simple... No need for insults. The electrons that were at the power plant are not now flowing through the computer monitor you are reading this on. If you really want to get technical, that's not entirely true. Some of them may well be. But that gets a bit deep into quantum theory and would simply be pointless in this discussion. The energy that the power plant converted from mechanical to electrical with a generator does make it to your house, but it was not carried along by a stream of flowing electrons like the water that flows into your home. But it was all possible due to flowing electrons. How are the electrons flowing through the conductors of an AC power distribution system fundamentally any different than water flowing in a hose? |
Herman The moniker contains the word simply, it was not an insult any more than referring to Mr. Romgard is. My apologies. I thought you had previously used "Simply" and then switched to "Simple" in the post I was replying to. I see now that you had used "Simple" previously. Because the electrons do not flow in a power distribution system. Yes, they do. There would be no power distributed if they did not. They do not flow along the wire like water flows in a hose. They do indeed. That is a simple analogy used to try and get people with very limited knowledge of the topic at hand to get some sort of visual picture so they might better understand, but it breaks down. It's a perfectly adequate analogy at the macroscopic level. Visualize this. Sure. AC voltage at 60 Hz reverses polarity every 8 milliseconds. Yes. In the electron flow = electric charge flow = water flow model the electrons would have to flow first in one direction and then in the other. Yes. Which is precisely what they do under AC conditions. If they didn't, your loudspeakers wouldn't work properly. The drivers' cones would only be able to move forward from their point of equilibrium. But of course they don't. The move both forward and backward from their point of equilibrium. That's because the current, and subsequently the electrons flowing through the voice coil is reversing direction, which changes the polarity of the magnetic field established in the voice coil which is what causes them to work in the first place. They would flow close to .7 the speed of light down the wire for 8 mS and then all turn around and flow back the other way for 8 mS and so on. A given electron would travel about a thousand miles and back 60 times a second. (186,000 m/s * .7 * .008) No. They do not flow close to .7 the speed of light. This is where your understanding is breaking down. You're confusing electron drift velocity with the velocity of propagation of the electromagnetic wave. It's the latter which will propagate at nearly the speed of light. Electron drift velocity is typically very slow (on the order of centimeters per second) and depends on how much current is flowing and how many electrons are available for conduction. Imagine a line of 100 people all pressed up against each other front to back. Then give a push to the person at the back of the line. The energy "wave" of that push will propagate along that line of people much faster than any individual is moving. It's much the same here. The electromagnetic wave propagates at a very high velocity, but the drift velocity of the electrons is very low. Ok, one more, in your model electrons are flowing back and forth, however, in real life the energy is flowing continuously in one direction, power plant to your house. How can the charge carriers (electrons) be traveling back and forth when the charges are all going in one direction? Because the charges aren't all going in one direction. At least not in an AC power distribution system. The charges are alternately moving back and forth. Do me a favor and google "electric current" and read through several of the definitions. They all say it is the flow of charge, nowhere does it say it is the flow of electrons. Thanks, but I've been studying physics and electronics long before the was Google. You're not understanding something very fundamental here. And that is, in this context, you can't separate "charge" from "electron." Electrons are negatively charged particles. And in a piece of metal wire, it is the electrons which are the charge carriers. Therefore the flow of charge means a flow of electrons. Can't have one without the other. Sure, electric current is ultimately broadly defined and can stem from flow of things other than negatively charged electrons, such as ions which which may be positive or negative, but we're not talking about any of that. We're talking about current flow in metal wires such as those in audio cables. I'm done. If you still insist that it is the flow of electrons then that will help you understand some of the basic principles so that is a good thing. I'm afraid you're the one who needs to come up to speed on some of the basic principles. You can start here: Electric Current. If you have any questions about it, just ask. |
Almarg Simply_Q, my statement, to which you agreed, implies that there is no "net" drift, just a drift back and forth over some small distance, the location of which remains essentially unchanged for any given electron. To understand why I use the term "net," you need to understand why I use it with the term "drift." "Drift" is used to distinguish from "movement." With no current flowing there is still movement. The electrons in the wire are moving about randomly in all directions near their Fermi velocity. And at any given point, the number of electrons crossing in one direction will generally be the same as the number of electrons crossing in the opposite direction. However if you apply an electric field, in addition to moving about at their Fermi velocity, the electrons will now take on a small velocity in the direction of the applied field. This is the drift velocity. And as a consequence, the number of electrons crossing that given point in one direction will now be greater than the number of electrons crossing in the opposite direction. In other words, there is a net drift in that direction. So, as long as there is current flowing, be it DC or AC, there will always be a net drift of electrons, because even if the direction of current changes alternately from one direction to the other, there will always be more electrons crossing that given point in one direction than the other. Does this make it more clear where I'm coming from? |
Herman As you realize, In a DC circuit the energy flows very fast from source to load and the electrons drift very slowly around the circuit. In an AC circuit the energy also travels very fast from source to load while the electrons vibrate back and forth, they do not drift. Despite these facts Mr. Q insists that they are flowing along the wire in an AC circuit. Your "facts" are wrong. They do indeed drift. With no drift there is no current flow. You are arguing that in an AC circuit, there is no current. This is simply absurd and demonstrates that you're rather out of your depth here. I think the confusion may arise from the term alternating current and thinking that current, like a river, is something that must flow. Where there is current, there is flow. Whether the flow is in one direction, or alternately in both directions. Reading back through my posts I admit I could have been clearer in my explanations. You're quite clear when you claim that there is no drift of electrons under AC conditions. And you're just as clearly incorrect. No drift, no current. Simple as that. I have the sneaky suspicion that Mr Q understands this better than he explains it too, but insisting that electrons flow from the power plant to the house like water flows from the pump station to the house makes it hard to come to common ground (no pun intended.) I never insisted any such thing. What I said was that power is ultimately delivered to your home as the consequence of electrons flowing in the wires of the distribution system. That's not the same as saying that an electron at the power generator ends up in your computer monitor. |
Almarg Simply_q, could you clarify what you mean when you say that electrons drift under ac conditions? Sure. Are you saying that they drift back and forth over a very short distance within the cable, as I indicated in my post yesterday? Meaning that a specific electron near the source end of the cable will never emerge from the other end of the cable (assuming there is no dc offset present)? Yes. My point has been that whenever there is any current flow (in this particular context), there must be a net drift of electrons. It matters not that the drift may alternate direction over time. To say there is no drift is to say there is no current. Or are you saying that they drift, to cite an example, all the way from the "hot" connection of the source component's output jack, through the cable and the input circuit of the destination component, then through the other leg of the cable to the ground connection of the source component's output jack, and then all the way back over that same route, but in the other direction, to the "hot" connection of the source component's output jack? No. Or something else? Only if you want to open up a can of quantum mechanics. :) |
Herman He is convinced in AC that there is a net flow of electrons from source to load. I never said any such thing. Please don't put words in my mouth. Mr, Q, has anybody come to your defense? No they have not. Why? You are wrong..... No one coming to the defense of an argument proves the argument wrong? What sort of twisted logic is that? |
Almarg Yes, it does. That is an excellent explanation, and as far as I am concerned our positions are now converged. Thank you. I'm glad were were finally able to uh... converge. Was it good for you *he says lighting up a cigarette*? ;-) |
Herman I get it now, you have redefined the word flow to suit your purpose. I've done no such thing. Everybody else in the world defines it as something that is moving forward, progressing. No, they don't. I would say that energy flowed in an AC circuit but the electrons vibrate about a fixed point never making any progress so they are not flowing. To even move about a fixed point is to progress as that is precisely what they're being directed to do under AC conditions. They would never make any progress only if they didn't do as directed. You define it at as any movement so electrons that aren't moving away from a central point but merely vibrate back and forth around that point are "flowing." No, I don't define it as ANY movement. I define it as DIRECTED movement, as is the case with electric current. I apologize for not picking up on that but you must forgive me for not knowing you had a different dictionary than the rest of us. The dictionary I have in front of me right now is Webster's Ninth New Collegiate Dictionary. Among its definitions of "flow" is: "to move with a continual change of place among the constituent particles" This well describes the electrons in this case, which is why we often refer to it as electric "current." And under "current" we find: "a FLOW of electric charge" You may find further reference to "flow" at Wikipedia under "electric current": "Electric current means, depending on the context, a FLOW of electric charge..." And under "alternating current": "In alternating current (AC, also ac) the movement (or FLOW) of electric charge periodically reverses direction." It would have helped the discussion if you had told us early on that you you had your own definition for words that differs from everyone else. I'm afraid you're the one who's out of step with common usage of the word "flow" as it relates to electric current. |
Herman To describe a back and forth motion as flow is just plain wrong. Use flow in a sentence that describes a back and forth motion. You can't do it. Sure I can. "Under AC conditions, electric current flows alternately in one direction and then the other." If that makes no sense, then there are countless physics and electronics texts which make no sense as "flow" is commonly used to describe electric current, both DC and AC and has been for over a century. That you're not aware of this leads me to suspect that either you've never studied physics and/or electronics to any degree and are arguing from ignorance, or you're disingenuously playing word games. However I'll give you the benefit of doubt and assume the former. But if you want to continue arguing against such well-established precedent, go ahead and knock yourself out. |
Herman If you take the time to read and think about my last few posts you will see my point has nothing to do with fuses or motor plates or amp clamps or anything like that. It only has to do with the fact that "flow of alternating current" makes no literal sense. But it does. I attempted to explain in a post yesterday, but it would seem the moderators took some issue with it and it was never posted. If this post is allowed, perhaps I'll try to explain again. The movement of the EM wave is not current. No, but it is the consequence of current. The magnetic field portion of the EM wave is entirely the result of the current flowing in the wire. |
Hey! Get in line! I still have two questions pending. ;-)
|
Herman I'm sticking with the idea that flow means something moving in one direction. But it doesn't mean that the direction never changes. Electric current is always flowing in one direction at any given time. The only difference between DC and AC is that under AC conditions, the direction changes periodically. But while the current is flowing, it's flowing in one direction. From the Oxford English Dictionary for flow: "The action or fact of flowing ; movement in a current or stream ; an INSTANCE or MODE of this." And for current: "That which runs or flows, a stream ; spec. a portion of a body of water, or of air, etc. MOVING IN A DEFINITE DIRECTION." Whether the current is flowing in one direction during one half of the cycle, or in the opposite direction during the other half of the cycle, it is indeed moving in a definite direction. It is an instance of flow. It is a current. An alternating current. I also believe you are backward regarding the relationship of EM wave and current. I also don't accept that you can talk about the M without the E. They are intertwined and inseparable.. Yes, they are intertwined, but that is irrelevant to the point I was trying to make. I was responding to your having said: "The fact that if using a wire there is a resultant moving about of electrons is really just a side effect. It is not the cause. They are wiggling about because there is an electromagnetic wave passing by. The wiggling about is not causing the wave." Specifically the last sentence. Keeping with the context of this discussion, i.e. audio cables, all your source component does is simply apply a potential difference across its outputs. It doesn't apply an electromagnetic wave as without a completed circuit such as connecting a cable between the source component and the downstream component, there will be no current flow. And without current flow, there can be no magnetic field. Now hook up your cables. The potential difference applied across them by the source component provides the electromotive force which causes the electrons in the cables to flow in the direction dictated by the polarity of the potential difference. It is only the flow of these electrons, these charged particles, which produces the magnetic field. So it is indeed the "wiggling" that's causing the wave. No wiggling, no magnetic field. No magnetic field, no EM wave. Since the wave can travel without current it is illogical to conclude that the wave is caused by the current the current. But it is. Whether it's the current flowing through your audio cables, or the current flowing through a radio antenna. It's all about the movement of charge. EM radio waves can travel down a wire but they can also travel from the transmitter to your radio no problem, no current. When that radio wave intersects your receiving antenna it sets the charges in motion, not the charges setting the wave in motion. In order to create the wave that sets the charges in motion in the receiving antenna, there had to have been charges in motion in the transmitting antenna which produced the radio wave in the first place. |
Herman Thank you for coming up with an example that conclusively proves my point. That flow is a poor choice to describe what we call AC current.
Conventional wisdom says, as you and others have pointed out, that in order to have current flow you must have a complete path. That is true in DC and because of that it makes sense to use the word flow with DC. However, something different is happening with AC. Nothing different happening with AC. At least not in this particular context, which I will remind you once again is audio cables. Specifically, analogue audio cables. Yes, in order to have current flow you must have a complete path. But you're confusing having a complete path with a given electron flowing through the entire length of that path. I have a battery. And a light bulb. I connect the light bulb to the battery with oh, let's say 100 feet of wire. The light bulb lights up. Ten seconds later, I disconnect the battery from the light bulb. The light goes out. Was there ever any current flowing during that ten seconds? Of course there was. However, the drift velocity of the electrons would have been slow enough that no given electron would have traveled more than a small fraction of the path. Now let's connect the battery again but in the opposite polarity as before. Again, the bulb lights up. And ten seconds later I disconnect the battery. As with before, no given electron ever travels more than a small fraction of the path. The only difference now is that they're flowing in the opposite direction from before. Was there ever any current flowing during that ten seconds? Of course there was. Now let's get fancy and hook up a switch between the battery and the wire that allows the battery's polarity to be switched. I flip the switch to one polarity for ten seconds, then the other polarity for ten seconds. Then back to the original polarity for ten seconds, and so on. Was there ever any current flowing during those 10 second periods? Of course there was. Now I do the same thing but at five second intervals. Was there current flowing? Yes. At one second intervals? Yes. At half second intervals? Yes. Quarter second? Eighth second? Sixteenth second? Yes. Yes. Yes. Hook up a radio transmitter to a cable that is several wavelengths long but has no load, it is open. An EM wave will travel the length and reflect back to the source. Google "time domain reflectometer" for a practical application of this phenomenon. I'm well aware of how TDR's work. In fact I've owned a couple in the past. So why isn't that an issue with audio circuits. It would be if the cables were approaching a quarter wavelength but that would be several miles at audio frequencies so it doesn't cause any problems. Right. But it IS audio circuits that we're discussing here. And my comments regarding current have all been within that context. And if you wish to address what I have said, then address it in the proper context. |
Herman How pompous is that? You give me permission to address you only if I do so in a manner you approve? If I say something in a particular context, and you wish to take issue with it, then yes, I expect you to do so in the same context in which it was said. So radio transmitters used to explain AC are off limits but you want to use batteries and light bulbs? We're discussing AC, not batteries, which are DC. Yes, I know we are discussing AC, and yes, I know batteries are DC. But if you alternately change the battery's polarity with respect to the pair of wires feeding the light bulb, you end up with an alternating current. You know, AC. This is fundamentally no different than your source component, preamplifier or amplifier, all of which are fed from a DC power source, and can even be powered from a battery, yet produce an AC signal at their outputs. Are you going to argue that audio components are off limits because they use a DC power supply? The battery in my example was nothing more than a power source. The end result was alternating current in the circuit attached to the power source. The transmitter example I gave was perfectly valid and you would know that if you understood the concepts. Your transmitter example was completely irrelevant in the context of what I had said and the argument I was making. We were discussing the appropriateness of using the terms "current" and "flow" as it related to AC. Specifically, in an audio system where the electrical wavelengths are vastly greater than line lengths. I could have addressed your comments in their own context, but the two situations aren't quite the same and would have to be discussed rather differently than had previously been discussed and I saw that as a distraction which would just further confuse those who may be reading this trying to understand things. If you can ONLY make your argument by invoking systems which are on the order of the wavelengths involved, then I can only say that your argument isn't holding water. If it did, then you could also make an argument in the context of a system which is a microscopic fraction of a wavelength. So let's just stick to the original context in which this issue arose. Again. Wrong. At what magic point does the cable get long enough that all of the sudden this magnetic field appears? Even with just a short length of cable there will always be some amount of parasitic capacitance which means there will always be some current flow as a result and subsequently a magnetic field. But talking about parasitics is just a distraction and I'm tired of distractions so let's get this back on track. This all started with your saying the term "alternating current" made no sense. I provided definitions of both "current" and "flow" from the Oxford English Dictionary which were quite in keeping with the notion of "alternating current." Instead of addressing that, you instead went off on some other tangent. So, no more distractions. Here they are again: Flow: "The action or fact of flowing ; movement in a current or stream ; an INSTANCE or MODE of this." Current: "That which runs or flows, a stream ; spec. a portion of a body of water, or of air, etc. MOVING IN A DEFINITE DIRECTION." Again, whether the current is flowing in one direction during one half of the cycle, or in the opposite direction during the other half of the cycle, it is indeed moving in a definite direction. It is an instance of flow. It is a current. An alternating current. Address this. No more distractions. |
I will now prove that the definition you are hanging your hat on describes motion in one direction. As I said previously, at any given time, the motion IS IN ONE DIRECTION. Not in two directions, or five directions or a dozen directions. But ONE DIRECTION. While the SPECIFIC direction may eventually change, you're still left with motion in ONE DIRECTION at any given time. Let me get my battery, polarity switch, 100 feet of wire and light bulb again. And I'd like to ask you two simple questions. I flip the switch one way for ten seconds. First question: Was there any "current" "flowing" during that ten seconds? Then I flip the switch the other way for ten seconds. Second question: Was there any "current" "flowing" during that ten seconds? |
I asked two simple questions which required no more than two simple answers. Instead of answers to those questions, I get personal attacks.
I'll try one more time.
I flip the switch one way for ten seconds.
First question: Is there any "current" "flowing" during that ten seconds?
I flip the switch the other way for ten second.
Second question: Is there any "current" "flowing" during that ten seconds?
|
Like I've been saying all along, give me one example besides AC where flow is used to describe periodic motion. Just so you won't have any more excuses to avoid answering the two simple questions I put to you. ALTERNATING FLOW of Non-Newtonian Fluids in Tubes of Arbitrary Cross-section
Single needle ALTERNATING FLOW blood pump system
To give adequate protection to erosion-susceptible soils subject to an ALTERNATING FLOW of water, it is vital that...
The Use of ALTERNATING FLOW to Characterize Porous Media Having Storage Pores
Screen Filter Module for ALTERNATING FLOW Filtration
Electromechanical controller for dishwasher with ALTERNATING FLOW
Study on ALTERNATING FLOW Hydraulic System : 1st-Report, Fundamental Consideration on a Single Phase System
There is a substantial difference between a straight-flow and ALTERNATING-FLOW steam engine In the working of the exhaust
The liquid medium may be supplied continuously to the vessel by a pump (16), while a piston (18) subjects the liquid medium to an ALTERNATING FLOW which ensures that the contents of each chamber (24) are well mixed and that the residence time for cells in the vessel (12) is substantially uniform.
Cardiac Cycle-Dependent ALTERNATING FLOW in Vertebral Arteries with Subclavian Artery Stenoses.
The science of swara yoga deals directly with this ALTERNATING FLOW of forces. Etc. etc. etc. |
|
One more time.
I flip the switch one way for ten seconds.
Question: Is there "current" "flowing" during that ten seconds?
I flip the switch the other day for ten seconds.
Question: Is there "curren" "flowing" during that ten seconds?
Two simple questions requiring nothing more than two simple, straightforward answers. Yet in spite of my having asked them several times so far, you've danced around and done everything you can to avoid answering them. Either there is "current" "flowing" during those ten seconds, or there isn't.
Which is it?
|
Herman So yes and yes, as long as you keep flipping the switch it flows back and forth. Ok. So you agree that when I flip the switch one way for 10 seconds, there is "current" "flowing." And if I flip it the other way for ten seconds, there is also "current" "flowing." Ok. Next question. When I flip the switch one way, the current flows in one direction. When I flip it the other way, it flows in a direction opposite the first. Is this "current" that's "flowing" not also "alternating" with respect to direction? Don't waste your time with a 200 word reply. A simple yes or no is all that's necessary. |
So there you go Q, the debate has come full circle. I kicked this off by saying it was a bad idea to use that phrase because it confused people and did not describe what was happening. "Alternating current" describes current which flows alternately in one direction and then the opposite quite perfectly. What is happening is current is flowing alternately in one direction and then the opposite. Can't think of a better description of that than "alternating current." Most people will tell you it means current is flowing to the load just like Jea. I don't see that as being due to any confusion CAUSED by the term "alternating current" and its common definition. It's a very easily understood concept. The only confusion I can see coming about would be trying to reach conclusions based solely on that basic concept without the benefit of knowing some circuit basics. Not by the concept itself. Your example with the switch has nothing to do with the common meaning of the phrase so it deserves no more attention. It has everything to do with the common meaning of the phrase. The common meaning of the phrase is current which alternately changes direction. You yourself agreed to this very thing. When I flip the switch in one position for ten seconds, there is "current" "flowing." When I flip the switch in the other position for ten seconds, there is "current" "flowing." When I flip the switch in one position, the "current" "flows" in one direction and when I flip the switch in the opposite position, the "current" "flows" in a direction opposite the first. Hence, we have an "alternating" "current." And if I keep doing this, we have an "alternating" "current" in which the change in the direction of "flow" is "periodic." We have the same thing whether I am mechanically flipping a switch that alternately changes the polarity of a battery or a power amplifier outputting a signal which alternately changes polarity. You can't seriously continue in that vein. It's you who can't seriously continue in that vein. That's because you've dug yourself into a hole. I saw you grab the shovel some time back when you said "How can the charge carriers (electrons) be traveling back and forth when the charges are all going in one direction?" That and your bit about the electrons flowing down the wire at nearly the speed of light. Then the word games started. |
Jea48 So if I understand you correctly even though the generator is putting out alternating voltage, where the voltage changes polarity, all a connected load sees is pulses. You can imagine the load seeing the voltage just as you'd see it on a 'scope, changing in magnitude and polarity. This results in a proportional current THROUGH the load, which you can imaging being just as you'd see it on a 'scope, only changing in magnitude and direction instead of polarity. |
Herman Q, I have completely destroyed any argument you've presented. You haven't even addressed in any valid fashion, let alone destroyed, the most salient and germane argument I have made. Instead, you could only resort to dismissing it out of hand as if that constituted some form of valid argument. You have resorted to games and other obfuscations from the very beginning. This all began with my statement that the water analogy was perfectly adequate in this context for explaining electric current, including alternating current. You disagreed with that statement. And here is the "argument" you presented: Water does actually flow i.e. a molecule of water that enters one end of a hose flows down the length of the hose and out the other end. The water molecules in your house started out at the water treatment plant and eventually made it to your home after being pumped into pipes.
Compare that to a power plant that delivers electricity to your home. The power plant is not forcing electrons onto the power grid that then travel many miles to your house. ... The electrons that were at the power plant are not now flowing through the computer monitor you are reading this on. The energy that the power plant converted from mechanical to electrical with a generator does make it to your house, but it was not carried along by a stream of flowing electrons like the water that flows into your home. Your argument consisted of taking one specific example out of many other possible examples and was among the least analogous to what you were attempting to comparing it to. I'll leave it to others to decide for themselves whether or not this was done intentionally. With just a little imagination, we can come up with an example that is more than adequately analogous for purposes of discussion here. We can take two pumps and two lengths of hose and connect the two pumps together with the whole assembly making up what would be analogous to a simple electric circuit. Then we can fill this "circuit" with water, the molecules of which would be analogous to the electrons in the conductors of an electric circuit. Now we can apply a force to the shaft of one of the pumps and cause it to turn. Energy is transferred from the shaft, to the pump's impeller, and then to the water which results in flow through through the circuit. This is analogous to applying a potential difference at one end of an electrical circuit. The result? Current. In this case, direct current. The flow of water molecules in the former, the flow of electrons in the latter. And in both cases, we measure current in terms of its rate of flow past a given point. Coulombs of charge per second in the case of electric current, and volume of water per second in the case of water. Further, just as energy is transferred to the load in an electric circuit--a motor for example--energy is transferred in this example to the impeller of the pump at the other end, causing its shaft to turn as a result. So we can see that the water analogy is perfectly adequate at explaining direct current. What about alternating current? Absolutely. There's nothing that says the first pump's shaft has to be turned only in one direction. It may just as well be alternately turned in one direction and then the opposite, subsequently causing the water to alternately flow in one direction through the circuit and then the opposite. In fact, we can continue this analogy and put together a power distribution system as Herman did in his original argument as to why the water analogy wasn't adequate to describe electric current. In a power distribution system, multiple electric circuits are magnetically coupled together via transformers to step voltage up for transmission, and down again for deliver yto your home. Instead of magnetically coupling two electric circuits, we can mechanically couple two water "circuits." If we couple the shafts of the second pump in our original water circuit to the first pump in a second water circuit using say gears or belt/pulleys, the energy from the first circuit will be transferred to the second circuit. If we use pulleys or gears of different sizes, i.e. different ratios, we can cause the shaft of the second pump to turn faster or slower than the first pump. The pump causes water to flow through the circuit by creating a pressure difference which is analogous to voltage or potential difference in an electric circuit. The faster the impeller turns, the greater the pressure difference and the slower it turns the lower the pressure difference. Hell, we can even use mechanical "diodes" to convert our alternating water current to direct water current. So, as I said originally, the water analogy is perfectly adequate for explaining electric current in the context being discussed here. And all the dancing and word games and other obfuscations doesn't change that. |
