Having the priveledge of teaching 1st year apprentices the question has come up that cant find an answer to. Do the electrons that are in motion creating current flow actually leave the armature of the generator and flow into the current carrying conductors creating a chain reaction of leaving and being replaced by the electrons in the material current is flowing in, and if not what causes the electron movement in the circuit conductors that are not in the magnetic field of the generator?
Electrical theory
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kwired
Electron manager
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My understanding of how this works is to think of a line of billiard balls to represent the electrons in the conductor.
Apply energy to the end ball and it will be transferred through the whole line and the last one will be the only one that moves very much. Now consider that in the conductor there is no end ball so they just keep bumping into each other transfering the energy on to the next one. There may be some flow of particles but it is not as fast as the movement of energy. With AC current that movement will be back and forth as polarity changes. In a DC circuit any movement will progress in the direction of current flow. This is likely the reason electrolosys can happen with a DC circuit but not an AC circuit.
Apply energy to the end ball and it will be transferred through the whole line and the last one will be the only one that moves very much. Now consider that in the conductor there is no end ball so they just keep bumping into each other transfering the energy on to the next one. There may be some flow of particles but it is not as fast as the movement of energy. With AC current that movement will be back and forth as polarity changes. In a DC circuit any movement will progress in the direction of current flow. This is likely the reason electrolosys can happen with a DC circuit but not an AC circuit.
gar
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kwired's description is good. Just consider that what is described as current flow is really a flow of energy.
If you go inside a vacuum tube with an electron emitter (cathode) and a plate electrode (an electron collector when positive relative to the cathode), then there is an actual flow of electrons from the cathode to anode. The velocity of this flow is a function of the electron charge, its mass, and the electric accelerating field (plate to cathode voltage). So the electrons do not move instantaneously from the cathode to the plate.
Back to the wire. There is a gradual average flow of electrons from one end to the other, but this is quite slow in comparison to the flow rate of energy. If you introduce a pulse of energy into one end of a wire pair the pulse will travel at about 0.6 to 0.8 times the speed of light. The velocity of light in free space is about 186,000 miles per second, or 982 feet per microsecond.
My photo P3 at http://beta-a2.com/cat-5e_photo.html shows 1.5 microseconds for the propagation time on a 1000 ft length of CAT-5E cable. This is a velocity of 667 ft/microsecond or about 0.68 times the speed of light.
Dow discusses vacuum tube electron transit time in chapter 2 of "Fundamentals of Engineering Electronics", 2nd Edition. Tube dimensions became important in the VHF frequency range because of this transit time.
For normal circuit analysis at low frequencies it is convenient to speak of current flow as being instantaneous, and it really does not matter whether or not that a single individual electron instantly goes around the path.
.
kwired's description is good. Just consider that what is described as current flow is really a flow of energy.
If you go inside a vacuum tube with an electron emitter (cathode) and a plate electrode (an electron collector when positive relative to the cathode), then there is an actual flow of electrons from the cathode to anode. The velocity of this flow is a function of the electron charge, its mass, and the electric accelerating field (plate to cathode voltage). So the electrons do not move instantaneously from the cathode to the plate.
Back to the wire. There is a gradual average flow of electrons from one end to the other, but this is quite slow in comparison to the flow rate of energy. If you introduce a pulse of energy into one end of a wire pair the pulse will travel at about 0.6 to 0.8 times the speed of light. The velocity of light in free space is about 186,000 miles per second, or 982 feet per microsecond.
My photo P3 at http://beta-a2.com/cat-5e_photo.html shows 1.5 microseconds for the propagation time on a 1000 ft length of CAT-5E cable. This is a velocity of 667 ft/microsecond or about 0.68 times the speed of light.
Dow discusses vacuum tube electron transit time in chapter 2 of "Fundamentals of Engineering Electronics", 2nd Edition. Tube dimensions became important in the VHF frequency range because of this transit time.
For normal circuit analysis at low frequencies it is convenient to speak of current flow as being instantaneous, and it really does not matter whether or not that a single individual electron instantly goes around the path.
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jaggedben
Senior Member
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The first part of the OP's question is about the interaction of armature and the field of the generator. I could be wrong, but I believe the answer is that no electrons flow from one to the other in the generator. The field causes electrons to move in the armature. But that is a magnetic field interaction, not a flow of electricity.
One clue is to look if the motor has brushes to connect to the armature. Most AC motors do not have brushes so there's no direct electrical circuit connection to the external source. Most AC motors depend on the field coils to induce current flow and magnetic field in the armature / rotor. Electrons move in the direction influenced by the applied electric field or the applied magnetic field.
Most or all AC corded tool motors have brushes because they are series connected universal AC / DC motors. This is because DC motors have very high torque at low speed. Wound rotor motors have brushes to take the induced rotor current out to an external resistor bank for reduced current / reduced torque at starting. Synchronous motors / generators have brushes to bring in an external DC source voltage to the synch field winding on the armature. The DC voltage generator is usually at the end on the motor shaft.
I believe this is the book I recommend as a reference, but I don't know. I loaned it out a long time ago and it's gone.
http://www.amazon.com/Electric-Mach...hapman/dp/0073529540/ref=cm_cr_pr_product_top
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