# why are there cables at different speeds if they are all made of copper?

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why are there cables at different speeds if they are all made of copper?

In: Physics

When signals travel through copper they create a magnetic field that in turn and induce signals on other copper wires. The solution for this is to have the cables twist around so that both of the wires recieved the same amount of noise, this is a balanced cable. I a cat 5 cable the there is 4 pairs of wires, and they all have a different number of twists per meter, allowing fewer places where the twists will line up perfectly parallel to eachother. In cat 6 the ratios are better, and also there is a plastic seperator to stop the wires from sitting so close together. You could technically try to put higher speeds through cat 5, but cross talk would just cause the data to corrupt.

Well not all cables are made of copper, gigabit cables are generally made of fiber optic glass which is why they transmit information so quickly, because it’s moving at the speed of light through glass. In general though it’s because speed is being externally set by whoever is sending it, ie throttling by the ISP.

The “speed” of a copper cable on a short run (less than 50ft) isn’t particularly related to the speed of a signal that passes through. It’s more related to how many signals can be passed through per second without loss. If you add more individual lines in the cable or increase how many signals you send per second, then you increase the speed. But if there’s interference between the lines or if the receiving device can’t read the signals as fast as they’re being sent, then the signal you’ll receive will be garbled.

In a physical example: if you’re trying to get 2000 cars from one side of a city to the other, increasing the top speed of the cars won’t help. Increasing the number of avenues and reducing the number of crashes (interferences) is the best way to do so.

A few things affect how fast data can be made to travel:

– diameter or guage of the wire. The thicker the wire, the faster the data can go.

– shielding (metal foil or braid around the wires and cable). To prevent external “noise” from affecting the signal, wires can be wrapped in metal foil (good) or metal braid (better). And the whole assembly or wires (the “cable”) can also be wrapped in foil (good) or metal braid (bestter). The best would be metal braid around the wires AND the whole cable.

– twisting pairs of wires. Wires can be paired and then twisted. Depending on how much twisting (# of twists per length) and how well the twists are maintained by the cable, the faster you can transfer data. This is why you can’t overtighten cable hold-downs, and you can’t (shouldn’t) bend cables more than the spec. The faster the data, the more you have to obey these rules.

– quality of the connecting pins & sockets, metal/plastic connectors, quality of construction (both factory and as assembled in the field). Things like how thick is the gold on the pins. Things like stripping off just the right amount of insulation. The faster your data is going, the better all these things need to be.