What is the difference between alternating current and direct current?

The difference is the direction of such current. An electric current is nothing more than a flow of electrons (particles that carry energy) passing through a wire, something like water circulating inside a hose. If the electrons move in only one direction, this current is called continuous. If they constantly change direction, we are talking about an alternating current. In practice, the difference between them lies in the ability to transmit energy to distant locations. The energy we use at home is produced by some plant and needs to travel hundreds of kilometers to reach the outlet. When this energy is transmitted by an alternating current, it does not lose much power halfway through. On the other hand, the waste is very large. This is because alternating current can easily have a much higher voltage than direct current, and the higher this voltage is, the farther the energy goes without losing strength along the way.

If all transmission systems were direct current, a plant would be needed in each neighborhood to supply homes with electricity. The only problem with the high voltage carried by alternating current is that it could cause fatal shocks inside homes. “Therefore, the high voltage is ultimately transformed into low voltages. The most common ones are 127 or 220 volts”, says physicist Cláudio Furukawa, from USP. Therefore, the current that arrives at your home socket continues to be alternating, but with a much lower voltage. Direct current comes, for example, from cells and batteries, as the energy generated by them, used in the devices that charge them, does not need to go far. There are also many electronic equipment that only work with direct current, having internal transformers, which adapt the alternating current that arrives through the socket.