The bare copper wire is a ground wire. if your old electrical system only has black and white, then you don't have a ground wire to hook the new fixture's ground to. Safest bet is to run a ground wire to that junction box (or hire an electrician to do that). If the box in the ceiling (I'm assuming its a ceiling fixture) is metal, the home's electrical system ground wire may be attached to the metal box itself. If that's the case, you simply need to attach your new fixture's ground wire (the bare copper one) to the metal box. If in doubt -- have an electrician look at it.
There has to be more to this question for a good answer. For the most part a light switch has two contacts, with a wire at each one. One live wire and another going to the light itself. There is also a neutral wire return (from the light to the electrical panel). There is only one live wire in any electrical circuit. [Please, don't flame me with examples of multiple electrical sources in circuitry. We're talking about home lighting.] If somehow you shorted the live wire from the switch to the electrical box (ground) or to another wire in the box, it was only momentary and you can just proceed with replacing the switch. It's a good idea to turn off the power first.
The materials conductivity will be one factor of an electrical wire.
Electrical wire sheathing should not project by more than one inch into where the wire terminates into a specific device. An example is a junction box or branch circuits terminating into a distribution panel.
The most important step is to make sure that the electricity is turned off to the project being worked on. Put a mounting bracket over the electrical box and tighten the screws. Twist the grounding wire to the grounding screw. Put the pendant together as per the instructions provided. Hold the canopy section near the electrical box. Using wire nuts, connect the wires from the canopy to the electrical box, keeping like colors together. Put the wire connectors in the electrical box. Using the hardware that the light came with, affix the canopy to the bracket. Turn the power back on and test to make sure it works.
if he had bunyans
One use for NiChrome wire is to make electrical heating elements.
Wire carries the electrical energy from one part to another
Yes. Instructions come in the box.
Run another wire from the electrical panel.
This is usually done by passing an electrical current through the wire.
Electrical wire sheathing should not project more than about one inch into the electric panel.