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Question about wires

  1. Sep 30, 2009 #1
    I've read that silver is the best conductor of electricity so I am curious why we do not use it in wires like we use gold,copper,etc....
     
  2. jcsd
  3. Sep 30, 2009 #2

    vk6kro

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    Silver is a good conductor but not all that much better than Copper which is a lot cheaper.

    As you can see from the following table of resistivities, Silver is only 8% better than Copper as a conductor
    Silver 1.59×10−8
    Copper 1.72×10−8
    Gold 2.44×10−8
    Aluminium 2.82×10−8

    Today,
    a Kilogram of Silver is worth US$526
    a Kilogram of Copper is worth US$5.84.
    Gold is worth US$996 per OUNCE or US$32021 a Kilogram
     
    Last edited: Sep 30, 2009
  4. Sep 30, 2009 #3
    Hello Mission Z-
    During WW II, one or more Calutron magnets (very big dipole magnets) at Oak Ridge used for separating U235 from U238 (isotope separation) had silver coils. This apparently was because copper for shell casings (ordnance) was in short supply, and Fort Knox had a very large stash of silver bars. I also understand that coils in military transmitters had solid, rather than silver-plated, coils. I think all of these silver coils have been melted down. The U.S stopped making silver coins about 1966.
    Bob S
     
  5. Sep 30, 2009 #4
    For the most part we use copper because it has good conductivity, and also because it's relatively cheap. Gold is used in high end applications, but as you can imagine it's expensive.

    The only other metal I know of that gets used commonly is aluminum for the main lines in houses and such.
     
  6. Oct 1, 2009 #5
    Copper is still a better conductor than gold. Gold is mainly used in connectors due to its resistance to corrosion.

    (unless with high end you mean hifi, where there are claims gold cables "sound" better :rolleyes:) (of course not backed up by any science at all, but that's not surprising considering they also use cable stands to give the sound some "air" :rofl:)
     
  7. Oct 3, 2009 #6
    I still see silver plating used in RF work. Due to the shallow skin depth at higher frequencies, it's practical to plate waveguides, resonators, and coils for matching networks. Thus Q values are increased and losses are reduced.

    I've also seen copper plated aluminum used for the center conductor of CATV lines. I assume this is because copper is more expensive than aluminum, but again, only a thin layer is needed.

    - Mike
     
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