In an electrical context, polarity is defined as the direction in which current flows in a circuit. In a DC system, there is likely to be a positive terminal and an electrical neutral point called ground, the 0V point. There is a bipolar DC system that includes both positive and negative voltage sides. By convention, DC current flows from the positive side to the negative side (or ground). The electrons move in the opposite direction. The polarity of alternating current is not always consistent, as the polarity usually fluctuates between positive and negative at 50 or 60 Hz. For a few reasons, however, when it comes to the components of an electrical system, it’s a little less clear. Let’s start with passive components that are often asked about, such as resistors.