Why AC is more efficient
You can transmit power more efficiently at higher voltages.
Unfortunately high voltages are dangerous in end-user applications.
With AC there is a neat device called a transformer which can turn a high-voltage, low-current current into a low-voltage, high-current one instead. Allowing you to transmit at an efficient voltage, and then deliver to houses at a safe one.
DC doesn't have an equivalent, so safe voltages don't travel long distances.
Cheers,
Ben
"... I couldn't see how anyone could be educated by this self-propagating system in which people pass exams, teach others to pass exams, but nobody knows anything."
--Richard Feynman
