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Topic: copper wire vs. steel wire  (Read 5927 times)

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Offline EdwardX

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copper wire vs. steel wire
« on: December 25, 2014, 12:56:48 AM »
in a generator or alternator magnets are passed by a coil of wires to induce a electromotive force. The electrons in the coil are repealed by the magnet or this would not work.  In metals like copper, silver, and aluminum their electrons are paramagnetic and repealed my magnetic forces.  However iron or nickel have unpaired electrons are are diamagnetic metals, so they are attracted to magnetic forces.  My question is can someone explain what would happen if one were to construct a generator with iron wires. how would that perform?

Offline Borek

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Re: copper wire vs. steel wire
« Reply #1 on: December 25, 2014, 04:46:32 AM »
The only important difference between iron and copper here is the specific resistance.
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Offline EdwardX

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Re: copper wire vs. steel wire
« Reply #2 on: December 25, 2014, 08:21:24 PM »
your reply does not address my question! Are you telling me the generator will function the same but less efficiently. how do you know, have you tried this?

Offline Arkcon

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Re: copper wire vs. steel wire
« Reply #3 on: December 25, 2014, 10:05:47 PM »
You're basically asking, "Can I wind a generator or alternator with steel wire, instead of copper?"

The is answer is yes, but the efficiency will suffer -- both because of the reason Borek: mentioned, and (something like) the reason you mentioned:  http://forum.allaboutcircuits.com/threads/help-can-you-wind-a-generator-with-steel-wire.20878/  Iron or nickel ferromagnetism result in the magnetic field becoming distorted, and not being avalible for induction.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline EdwardX

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Re: copper wire vs. steel wire
« Reply #4 on: December 26, 2014, 01:05:13 AM »
thank you Arkcon! My question stems from my confusion of how electrons respond to a magnetic field! It seems electrons can be attracted or repealed by a magnetic field depending on if their own magnetic field is in line with the outside field! If light(be it visible, ir, radio ect) interacts with an electron, lets say the oscillating magnetic field of light causes the electron to oscillate by conflicting with its magnetic field, which would explain the photoelectric effect, but how is this different from the way the orthogonal "electric wave" of light interacts with the electron?  What is the difference between electric and magnetic forces?

Offline Enthalpy

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Re: copper wire vs. steel wire
« Reply #5 on: December 31, 2014, 03:26:48 PM »
Some pieces of answer:

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Copper brings the second best resistance and is cheaper than silver. Aluminium is worse at equal volume but better and cheaper at equal mass, so it's used regularly where volume isn't a limit, in high-voltage power lines; it's uncommon where volume is a limit (as more conductor volume increases the unwanted length of the magnetic path), but one TGV train version uses aluminium in its transformers.

Beyond DC resistivity, the magnetic permeability of iron makes it horrible as an AC conductor. Any conductor carries the current only at its surface as the frequency increases (9.3mm for Cu at 50Hz, worsens as sqrt(frequency)) but in a ferromagnetic metal, this "skin depth" is further divided by sqrt(relative permeability), so Fe is unuseable at 50Hz already.

There are less obvious but strong reasons more. For instance in a motor, you want the magnetic flux created by the rotor to pass to the stator, not to close within the rotor. Ferromagnetic conductors would be fatal to this "slot inductance". As well, the induction through the wires must be minimized to reduce losses by eddy currents in the wires, excluding iron again.

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Individual electrons are not dia-, para- or ferro-magnetic. This behaviour is for electrons near nuclei, forming orbitals or bonds, depending on whether the electrons make pairs or not, and in the case of ferromagnetism, is strictly a collective behaviour.

Dia- and para-magnetism are very weak; it needs special setups to observe them. Only ferromagnetism is strong enough and is used in common electric machines. In ferromagnetism, electrons interact enough with their neighbours to be completely oriented permanently, to make inductions like 1-2T thanks to the collective behaviour, which enables electric machines. Coils only influence the orientation of this spontaneous magnetism, and only where "Weiss domains" of conflicting orientation meet, so electrons are easier to flip there.

You could seek more information by searching expressions like ferromagnetism, soft magnetic, permanent magnet, diamagnetism, paramagnetism, Weiss domain, magnetic domain, Bloch wall, Kelvin effect, skin depth, slot inductance, leakage inductance. Wikipedia is a good place to start.

Offline EdwardX

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Re: copper wire vs. steel wire
« Reply #6 on: January 12, 2015, 01:31:24 AM »
Thank you, any tips on where to look to research these "eddy currents" you speak of that arise from induction?  Someone else brought them up recently and I am extremely interested!

Offline Borek

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Re: copper wire vs. steel wire
« Reply #7 on: January 12, 2015, 03:08:28 AM »
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Offline EdwardX

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Re: copper wire vs. steel wire
« Reply #8 on: January 12, 2015, 12:45:15 PM »
hahaha

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