The majority of today’s electronics either do or can run on DC current, and must be converted from AC, which comes out of wall-outlets, in order to run. In addition, DC is safer – according to IEC 60479, it takes about four times as much DC current to kill a man than AC current. So why do we use AC? There are three main reasons:
- AC electricity loses less power over power lines than DC.
- It’s easier to change the voltage of an AC current, and the higher the voltage, the less power is lost. This is why non-residential power lines are more dangerous than residential power lines: they have a much higher voltage to reduce power loss over long distances. In fact, it’s so high that the surrounding magnetic field physically repels birds from landing on the wires
- It’s easier to convert from AC to DC than the other way around. A DC power supply consists of a transformer, a capacitor, and a few diodes, all of which are cheap and non-mechanical (no moving parts). A non-mechanical DC-to-AC "inverter," however, is not so simple (which was doubly true before the invention of the transistor).
There are also historical reasons – see the War of Currents.
Additional Reading:
- Do transformers obey Ohm’s Law?
- (Un)Common Questions about Electricity
- How is it possible that there’s not a complete circuit to the power plant?
- What’s the difference between “voltage at a point” and “voltage between two points?” Also, what is ‘ground?’
- What’s the difference between neutral and ground?
