Direct current, DC
Direct current (DC) flows only in one direction of the conductor. In the DC circuit, the terminals of the battery always maintain a constant polarity. The electrons inside the conductor are mostly chaotic and move to the (+) pole of the battery little by little due to the voltage applied to the circuit. When installing the batteries, be sure to check the polarity.
Alternating current, AC
In alternating current(AC), Electrons only oscillates. This is because the voltage of the circuit changes periodically.
Since the household power source is AC, there is no polarity indication on the power outlet. The AC power frequency of Korea is 60Hz. In other words, the process of returning to the original state by changing the voltage is repeated 60 times per second. Electronic products that use AC power do not need a polarity mark, so you do not have to worry about (+) or (-) polarity when plugging in.