## How It Travels

Physics tells us how electricity can be generated and used, but without some way to transport the energy from the producer to the user, the whole system is useless. Consider a battery sitting on a table with a light bulb sitting next to it: there's quite literally a "missing link" between the two, preventing the bulb from lighting up as we'd like it to.

That gap has to be filled by some material that lets electrons travel freely through it from one end (the battery) to the other (the bulb). A material that lets electrons through is called a conductor, and all metals are by definition conductors. However, some metals are better conductors than others -- and the worse the conductor, the more resistance it gives off in the form of heat, which is bad [for more on that, go here].

The crux of the matter is that we'd like to use something that conducts very well -- something that lets electrons travel through extremely easily. In ordinary wires used in houses and labs, we generally use copper. Since copper wires are usually coated with protective plastic, the metallic core is not always obvious, but it is always present, because plastic can't conduct electricity! In fact, that's the reason plastic is used.

So we can use copper wire as the missing link to connect a battery and a light bulb -- in more general terms, to connect the producer and the consumer. Since copper is a conductor, electrons flow freely through it, lighting up the bulb once they get there.

On a larger scale, the power that travels from a, say, nuclear power plant to your home works in the same way. In this case, the wires are just very thick and very long. But although they conduct well, the farther the electricity has to travel, the more resistance becomes an important factor. That means that the longer the wire, the more energy is lost as heat, and the less energy actually arrives at your house. There is a limit to how long the power lines can be, and that is why your power comes from relatively nearby (usually from within the state or bordering states -- a web site showing electricity grids is here).

But there is an added complication.

electric currents

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