Why Does the North Pole Determine the Live Wire in AC Generators?

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Discussion Overview

The discussion revolves around the determination of the live wire in AC generators, specifically focusing on the role of the north pole of a magnet in this context. Participants explore whether this determination is based on a natural phenomenon or an arbitrary convention, and they examine practical implications and testing methods related to household wiring and generators.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Experimental/applied

Main Points Raised

  • One participant suggests that the side of the coil cutting the magnetic flux from the north pole first becomes the live wire, questioning the reasoning behind this.
  • Another participant argues that the designation of live and neutral wires is arbitrary and could be reversed, emphasizing that the north-seeking pole of a magnet is treated as special due to its navigational significance.
  • Some participants challenge the idea of it being a convention by pointing out that practical tests, such as using a tester at a neutral socket, show that the north pole is considered superior in practice.
  • It is noted that both live and neutral wires carry full current, and neither pole of the magnet is inherently better than the other.
  • Participants discuss the implications of testing household sockets and the differences between North American 110v and 240v outlets, suggesting that the neutral wire's behavior is influenced by grounding and industrial regulations.
  • One participant proposes a hands-on experiment with a coil and a bar magnet to test the concepts discussed.
  • Questions are raised about the consistency of the live wire designation if the generator is turned off and the coil's orientation changes.

Areas of Agreement / Disagreement

Participants express disagreement regarding whether the determination of the live wire is a natural phenomenon or an arbitrary convention. There is no consensus on the implications of testing methods or the nature of the live and neutral wires.

Contextual Notes

Participants highlight the complexity of testing household wiring and the influence of regulations on wire designation. There are also unresolved questions about the behavior of generators and the implications of changing orientations.

americast
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In an AC generator, the side of the coil which cuts magnetic flux link from the north pole first becomes the live wire. Is there any reason behind that or is it just a natural phenomena?

Thanx in advance...
 
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It's an arbitrary convention. You could easily do it the other way around.

Aside:
By "north pole" you mean the north-seeking pole of a magnet.
The "North Pole" is the place on the Earth's surface where the star Polaris is directly overhead
... this is close to the Earth's magnetic south pole.

The North-seeking poles of magnets are treated as special because of their relationship to Polaris and use in navigation. It's like the preference for a right-handed rectangular coordinate system.
 
How could it be a convention? If you place a tester at the neutral socket of any plug point in your home, you won't find it glowing... This simply shows that in reality (or by nature), north pole (of the magnet) is being considered superior. Anyway, I would like to know how you can easilydo it the other way round.

Thanx...
 
Both the live and neutral wires carry full current. Neither pole of the magnet is intrinsically better than the other.
 
Again... if you place a tester at the neutral socket, it won't glow...
 
americast said:
How could it be a convention? If you place a tester at the neutral socket of any plug point in your home, you won't find it glowing... This simply shows that in reality (or by nature), north pole (of the magnet) is being considered superior. Anyway, I would like to know how you can easily do it the other way round.

Thanx...

Are you thinking in terms of a North American 110v outlet? If so, the neutral isn't connected to the power source at all, it's connected to ground so of course it doesn't light the tester. To see the symmetry between current generated by cutting the north field lines and the south field lines you have to use a North American 240v outlet, both of whose legs will test hot.
 
Testing this out of a household socket introduced other variables, such as what Nugatory has said. Why not make your own coil, connect it to a loop of wire, and then stick a bar magnet in and out? Test this for yourself!

Zz.
 
americast said:
Again... if you place a tester at the neutral socket, it won't glow...
Where a neutral (household) wire tests zero, it is by convention - the household wiring, and probably the tester itself, is designed that way because of industrial regulation.

As the others have said: not a fair test.
Test an actual generator that you control.
 
Last edited:
americast said:
In an AC generator, the side of the coil which cuts magnetic flux link from the north pole first becomes the live wire.

Do you have a link or reference for this? What type of generator are you talking about?
 
  • #10
nasu said:
Do you have a link or reference for this? What type of generator are you talking about?
... because - imagine you switched off the generator and it spins down so the other part of the coil is the first to cut the north pole ... does that mean you have to go around and recolor all the wires? Or do you have to hand crank the loop around so it's the same again as it was last time?
 

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