h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

- The fact that the direction of AC changes many times a second creates a fascinating side effect known as the 'skin effect'. This means that the current only flows through the surface of the wire. As such, losses due to resistance are greatly reduced and AC power stations have a much greater range.

That's plain wrong. When current only flows through the SURFACE, the effective cross section AREA of the wire gets SMALLER, thus INCREASING the resistance.

Also, distributing some power with same efficiency requires using higher peak voltages for AC than DC, because AC isn't at 100% all the time.

DC is being used in public transport, and now when efficient AC-DC conversion is possible, power lines using DC are attractive again.

Though it makes little sense to all but a few very educated or naturally brilliant people (no I'm not one of them), A/C power doesn't actually change directions. It reverses polarity (negative to positive) back and forth as it is generated. American-generated electricity does this 60 times per second, while European does it 50 times a second (arguably a more efficient system). Due to this, it causes the conductors to generate an electromagnetic field. This property is what is exploited in transformers to step up or step down the voltage or amperage.

While D/C power is more efficient in shorter distances, A/C works better over long distances. Most of the home appliances that you have contain devices to convert the A/C power to D/C to work, which is why so many of them work with batteries.

Distributing power with A/C is also more efficient than D/C because, while there are higher peak voltages, it can be manipulated easier than D/C. The peak voltages are only in existance for 1/60th (or 1/50th) of a second, so they are largely ignored by most engineers.

For the record, I'm not an engineer, I'm an electrician. I work with electricity every day, and while I don't fully understand how it works, I know how to manipulate it.