Why is some copper wire from say a winding in an electric motor bright gold and other like speaker wire is white. are they both copper or is one copper with an alloy?
copper wire is well copper colored. Speaker wire that is silver is an alloy. Copper is expensive. currently the amount of copper in a penny is worth more than $0.02. so if you were to sell 100 pennies you would get $2 plus for the copper. Enough so that the feds recently made this illegal. The color is there so that you can tell the polarity of the current running through the wire.
Different wires are made with different alloys to accommodate their intended use. Correctly wire used as winding is coated to prevent oxidation, hence the color.
Copper wire in windings must be insulated. This is done with paints and enamels. These enamels are the colors that you can see. If you scrape them then you will see the true copper underneath.
They are both coated with an enamel paint which serves as an insulator. It depends on the color of the paint.
The conductor portion of all copper wire is ... well ... copper-colored. Some applications requiring very fine stranding (like speaker wire, for example) include either a copper alloy or some strands of another conductor (usually gold or silver). Heavier gauge materials (like motor windings) are basically pure copper, or at most have a small percentage (< 1 percent) of silver for strength included in the alloy mixture. Most of the coloring on wire is from the insulation used to protect the stranding. Motor windings often have a thin film of insulation applied directly to the strand to prevent the development of shorts and grounds. Speaker wire MAY have insulated stranding, but more often simply has a composite jacket that does much the same thing. Motor windings may also have additional layers of tapes or other insulating materials applied to create a coil, in cases where the varnish-type insulation is insufficient (from either an electrical or mechanical perspective). The purpose of introducing silver or gold stranding into speaker wire is to ensure that the correct polarities between speaker and line driver (amplifier) are maintained.
