Why are some wires (especially thin ones, like ones connecting a battery pack in a toy) made up of many wires instead of just being one solid piece of metal?
1) it is more flexible than single wire of same resistance, that is you can bend it to more angle than it's counterpart single wire that would have same resistance. 2) AC current don't flow over whole cross section area of a wire but it flows more near/on outer surface of wire. So resistance is not a function(inversely proportional) of cross section area for AC current but surface area wich is more for for many wires cable than single wire cable for given weight of wire material and thus it will have lesser resistance. 3) it is more reliable, that is if one of many wire get beaked the wire will still work unlike single wire cable.
It's called stranded wire. A solid wire is rigid and will break after only a few times bent. Solid wire is cheaper and is used in house wiring where it does not need to flex. But even automotive wiring uses stranded wire because otherwise the vibration would cause breaks in no time. You may get some answers about high frequency skin effects but few people actually understand it and most of the information about it is wrong.
They are more flexible and even in the case of some of the small wires be broken, it still conducts electricity
Easier to bend the wire without breaking.
Electrical wires can produce noise. To reduce the noise they needed to twist it and add more wires into it. Some wires have many threads of wires inside an electrical wire to carry more data. An example is a Coaxial cable.
