What colour is the solid copper?

Answer 1

• bare copper wire is copper orange color.
• tinned copper wire is silvery color.
• enamel coated copper magnet wire can come in any color, depending on enamel.
• plastic coated copper hookup wire can come in any color, depending on plastic.

copper wire for household wiring is color coded using plastic coating:

1. black - hot 120 VAC
2. white - neutral 0 V current return
3. green - ground 0 V safety return (no current normally)
4. red - hot 120 VAC, opposite phase from black for use in 240 VAC hookups
5. etc.

copper wiring for industrial 3-phase power has additional colors, which I won't visit here.

copper wire for electronic use follows an entirely different color code:

1. red - positive DC power
2. black - DC return
3. green - negative DC power, or signal if no negative power
4. other colors - signals

don't confuse color codes!

Answer 2

Black and forms a blue solution when dissolved in water.