If electron flow with alternating current keeps changing direction, then = it seems that current doesn't move along a path from one point to = another, but instead moves back and forth. Yet AC wiring books describe = current as moving from the hot/black side, through the load, and = returning via the neutral/white side.
How does AC move along a path when the direction of current keeps = changing? Thanks for any insights, Jerry
seems that current >doesn't move along a path from one point to another, but instead moves back and forth. Yet >AC wiring books describe current as moving from the hot/black side, through the load, and >returning via the neutral/white side.
The current moves to and fro, and does its work. A light bulb, for example, gets just as hot when the current is going right-to-left as when it goes the other way. No net movement of electrons is necessary. Then why call the wires different names? To keep track of which wires have voltage with respect to each other. At any instant in time, whether they are plus or minus with respect to the other kind of wire, two hot wires will have no voltage between them, and the same is true of two neutral wires. Also, the neutral is connected to ground somewhere, and its important for safety reasons to know which wire has little or no voltage with respect to ground.
Think of sound. The air molecules move back and forth but do not travel = from the source to the listener. Yet we still think of the sound = traveling from one point to another. Don't confuse the wave with the = medium. Waves move though the medium doesn't.
How does AC move along a path when the direction of current keeps = changing? Thanks for any insights, Jerry
Current isn't the movement of any electron, but the net movement of charge through the conductor, at any point. While an electron is going one way (and moving a tiny fraction of an inch) the current it is part of is moving in that direction, from the power generator to your house. when that electron turns around, the current anywhere along that path from generator to house goes the other way. This is because the distance from the generator to your house is a small part of a wavelength at that low frequency.
When you raise the frequency to the signals arriving through the cable television system, this assumption of uniformity direction all along the path, is no longer valid.
Then they are mistaken.
The distinction between hot and neutral is that the potential (voltage, not current) on the neutral wire with respect to Earth is low (they are connected together at the power panel and at the transformer on the pole). The voltage between the hot conductor and Earth is much higher. So connecting a load between hot and ground is quite similar to connecting it between hot and neutral. If you are standing on a dirt in your bare feet and you touch the hot wire, you will understand why they chose this word to describe that side of the circuit.
On Sun, 08 Oct 2006 12:41:13 GMT, in message , "Jerry" scribed:
then it seems that current doesn't move along a path from one point to another, but instead moves back and forth. Yet AC wiring books describe current as moving from the hot/black side, through the load, and returning via the neutral/white side.
First of all, you mistake electron flow for charge flow. Current is not electron flow, rather it is charge flow. One amp is defined as one Coulomb of charge per second passing a given point.
Second, about your confusion: the books you talk about are making a simplistic description of the connections being made in a circuit. The supply side and the return side are necessary labels, helpful when building or maintaining circuits.
If there is no path, charge cannot move at all. So if charge is moving, there must be a path. Think of a million hikers on a single-file trail. The path is there, and the hikers are there, but they cannot decide which way to go, so they sway back and forth. The ends of the trail show the movement of the individual hikers within the trail; the energy of their movement goes back and forth, and is noticeable.
I have always understood charge as the flow of electrons if it is a metal conductor. If it is not a metal conductor then charge is not necessarily electrons.
On 8 Oct 2006 20:56:03 -0700, in message , "Wayne" scribed:
Charge is the energy produced when electrons move. A potential is introduced at either end of the circuit path, which imparts energy to the electrons in the conductors, causing them to move, which in turn creates a net flow of charge. Charge has no mass and moves fast, close to c. Electrons have mass, and move rather slow when excited. I wonder what fundamental element moves in a non-metal conductor? Neutrons?
OK, best to leave the non-instructive, derisive satire to Phil Allison. Er, except he's too dull for satire. Ah well, sorry. Charge does not flow easily in non-metals (insulators) because elementally, they have few free electrons, which means it is difficult to jostle them loose with potential energy. Thus, you can apply voltage to a ceramic, or glass, and its electrons will not budge, hence no charge will be produced.
Now, if you're talking about hole flow in a semiconductor, that's a whole new bucket of worms; are you sure you want to go there?
Those wiring books are describing the physical path of a circuit in a way people who know nothing about electricity can wrap their heads around. They don't need to know if it is AC or DC, worry about phase or anything else. They just need to know how to hook up and outlet or a light and switch. Some electricians don't know any more than that, yet they can do good work that passes inspections.
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They don't tell you the whole story, (I don't know who wrote this!). AC as my teacher told me is a sinusoidal effect consisting of "positive" (whatever it means) and "negative" half-waves. So what is "hot" and "neutral" changes every half-cycle. Consider a steam engine piston, moving forth AND back and yet doing "work".
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